Mismatched tyres

[Katman]

I'm interested to hear peoples opinions of mixing a crossply tyre with a radial.

Yay or nay?


(To the moderators - I've placed this thread here instead of the Brakes, Wheels, Tyre sub-forum because I'd like to hear as many opinions as possible.)

[CookMySock]

I think most people are going to be wondering why you might run a crossply tyre to start with.

Maybe a bit more background?

Steve

[Katman]

I think most people are going to be wondering why you might run a crossply tyre to start with.





Well, for a start, there aren't radial tyres to fit my bike.........

But this isn't about my bike.

[Skyryder]

I'm interested to hear peoples opinions of mixing a crossply tyre with a radial.

Yay or nay?


(To the moderators - I've placed this thread here instead of the Brakes, Wheels, Tyre sub-forum because I'd like to hear as many opinions as possible.)

Not wise.

Can I Mix and Match?
That might work for your wardrobe, but not your tires. In general, the brand and model for the front and rear need to be the same. In some cases, the tread pattern is similar enough to mix. Some Pirelli and Metzeler tires, for example, are compatible. It would be best to check with a reputable dealer to be sure. Mixing two tires whose tread patternaren't compatible can have deadly results. They won’t work properly together. Tires are made one of two ways: Bias ply or radial. Some bikes that come equipped with bias ply tires cannot be fitted with radials, and vice-versa. Again, check with your dealer. NOTE: (NEVER mix a bias ply with a radial!)

From

http://www.spokes-women.org/Technical_Cornor/motorcycle_tires.htm


Skyryder

[riffer]

I thought it was a no-no, as the biasply front and radial rear would cause massive understeer problems and the opposite would cause oversteer.

HOWEVER, this was ages ago and times change.

The Harley-Davidson Rocker runs a radial rear and a biasply front.

And they wouldn't sell anything that could be that dangerous given that they're from USA - the land of the law suit.

[MSTRS]

When radials first began appearing for cars, the advice was, if mixed, to put the radials on the front. Not sure if that applies to bikes tho.
Also not sure about mixed tread patterns...
The job of the front tyre is to force a 'dry' patch on the road for the rear to travel on. That only works in a straight line. At a lean, this is out the door, regardless of tread pattern.

[NordieBoy]

I thought it was a no-no, as the biasply front and radial rear would cause massive understeer problems and the opposite would cause oversteer.

So bias-ply front and rear and you're 2 wheel drifting everywhere?

[jono035]

So bias-ply front and rear and you're 2 wheel drifting everywhere?

That'd be worth seeing...

[boman]

Crossply tyres, due to their construction, are stiffer in the sidewall and carcass than the Radial tyre. Radial tyres are made so that the sidewall can flex and keep the tread pattern in better contact with the road. Mixing the types is not recommended, due to their different construction methods. On a car, or truck, from memory ( I am often wrong) crossplys on the front and radials on the rear is the recommended method. Mixing them on the same axel is, from memory illegal.

[MSTRS]

Crossply tyres, due to their construction, are stiffer in the sidewall and carcass than the Radial tyre. Radial tyres are made so that the sidewall can flex and keep the tread pattern in better contact with the road. Mixing the types is not recommended, due to their different construction methods. On a car, or truck, from memory ( I am often wrong) crossplys on the front and radials on the rear is the recommended method. Mixing them on the same axel is, from memory illegal.

Nup. Radials will hang on for longer than a crossply. If you 'want' a tyre to break traction it'd better be the back first. Surely.

[boman]

Nup. Radials will hang on for longer than a crossply. If you 'want' a tyre to break traction it'd better be the back first. Surely.

Yea but the crossply on the rear will not allow the bike to corner properly, I think. They tend to push the front end around, which is why you want the crossplys on the front, not the rear.

But I stand to be corrected on this. My experience in tyres is more automotive than motorcycle. I know, on a car, that if you put crossplys on the rear, then you will struggle to drive around a corner.

[Skyryder]

Crossply tyres, due to their construction, are stiffer in the sidewall and carcass than the Radial tyre. Radial tyres are made so that the sidewall can flex and keep the tread pattern in better contact with the road. Mixing the types is not recommended, due to their different construction methods.


I think that is the 'nux' of the problem.

With different tyre walls you will have a difference in how each tyre behaves. Put these differences together on a motorcycle frame and the traction of the bike will not be as stable. That's how I see it.


Skyryder

[boman]

I think that is the 'nux' of the problem.

With different tyre walls you will have a difference in how each tyre behaves. Put these differences together on a motorcycle frame and the traction of the bike will not be as stable. That's how I see it.


Skyryder

On a car the differences are noticable. On a bike I would think they would be very noticable, dangerous even. I wouldn't like to try it.

[CookMySock]

If you are stuck with having to fit crap tyres, maybe some suspension work is in order to recover the situation.

Steve

[Katman]

If you are stuck with having to fit crap tyres, maybe some suspension work is in order to recover the situation.

Steve

Don't try and second guess the question.

You're already shown you don't know the first thing about tyres.

[boman]

If you are stuck with having to fit crap tyres, maybe some suspension work is in order to recover the situation.

Steve

Just don't mix crossplys and radials on the same bike.

[scracha]

I'm interested to hear peoples opinions of mixing a crossply tyre with a radial.


Isn't that illegal?

[AD345]

Isn't that illegal?

Either way it would be interesting to know what an insurance company thought of it...

[Katman]

To give you a brief run down...........

I know of someone (yes, they're a member on here) who asked a bike shop to get in a Pirelli Sport Demon (crossply) front tyre to match his rear tyre. The shop obviously never got around to ordering it and when the customer came in to get it fitted, they decided to fit a Metzeler M3 instead, simply because that was all they had in stock.

And yes, there is a lot more to this story than I have told so far.

[cs363]

I thought it was a no-no, as the biasply front and radial rear would cause massive understeer problems and the opposite would cause oversteer.

HOWEVER, this was ages ago and times change.

The Harley-Davidson Rocker runs a radial rear and a biasply front.

And they wouldn't sell anything that could be that dangerous given that they're from USA - the land of the law suit.

I would have thought it a no-no too, but it's interesting about the HD Rocker - though this is obviously a bike that isn't going to demand too much of it's tyres in comparison to a sports bike for instance.

Given that as Riffer correctly states, the US is home to the law suit for anything that may be even remotely dangerous to the vehicle operator, this would tend to indicate that whilst not ideal this combination is at least possible.
I guess it would come down to the bike and it's intended usage, bearing this information in mind. Modern bias ply tyres are very good and light years ahead of the stuff we used to use back in the old days when that was all you could buy.
Any clues as to the bike that generated this question Katman? :)

[cs363]

After checking the relevant sections of the LTSA website it would appear that the only legal requirement regarding radial and bias ply tyres is the commonly known one regarding the fact that they should not be mixed on the same axle.
http://www.ltsa.govt.nz/certifiers/virm-in-service-wof-only/motorcycles-10-v3.pdf
http://www.ltsa.govt.nz/rules/tyres-and-wheels-2001.html

So it would seem the authorities are OK with it, unless of course I've missed it on the LTSA's wonderfully easy to navigate website.... *choke*

[Jantar]

To give you a brief run down...........

I know of someone (yes, they're a member on here) who asked a bike shop to get in a Pirelli Sport Demon (crossply) front tyre to match his rear tyre. The shop obviously never got around to ordering it and when the customer came in to get it fitted, they decided to fit a Metzeler M3 instead, simply because that was all they had in stock.....

Depending on the bike I would think that would be a dangerous combination. Different profile as well as different tyre construction is asking for some rather interesting handling characteristics. Personally I wouldn't even take a bike with that combination out of the shop.

[Kickaha]

When radials first began appearing for cars, the advice was, if mixed, to put the radials on the front.

The correct recommendation on a car is radials to the rear


If you are stuck with having to fit crap tyres, maybe some suspension work is in order to recover the situation.

Steve

There are still some very good crossply bike tyres available, you can buy crap radials as well

[Katman]

And yes folks, there's even more to this story.

I don't intend to elaborate further - if the person it happened to chooses to do so, that's his business.

I'm hoping that if the shop in question reads this thread that they may revise their attitude towards him.

[cs363]

:nono: Hmm...certainly not a good look for a so called professional shop to be doing something like that regardless of legalities, especially without the customers OK on it. Particularly on a bike designed for radials that are presumably readily available.
Almost calls for a name and shame, but I understand your reticence to do so particularly if it's down to one squid employee for instance, as one squid does not a whole bad shop make, in the same way as one bad dealer does not make an entire industry bad.. :msn-wink:

[Katman]

:nono: Hmm...certainly not a good look for a so called professional shop to be doing something like that regardless of legalities, especially without the customers OK on it. Particularly on a bike designed for radials that are presumably readily available.
Almost calls for a name and shame, but I understand your reticence to do so particularly if it's down to one squid employee for instance, as one squid does not a whole bad shop make, in the same way as one bad dealer does not make an entire industry bad.. :msn-wink:

Trouble is, on my suggestion, the person in question has been back into the shop to question them on the issue and has been told that the shop has no problem with what they have done.

[cs363]

Trouble is, on my suggestion, the person in question has been back into the shop to question them on the issue and has been told that the shop has no problem with what they have done.


Umm.. :gob:

[wickle]

always been told and have done, replace front and back at same time with matched tyres, if you chew back tyres out buy two and store reserve in back of garage, most probably will find better wear out of second trye as it has had time to cure properly.

[riffer]

Trouble is, on my suggestion, the person in question has been back into the shop to question them on the issue and has been told that the shop has no problem with what they have done.

Interesting. Did you fail the bike on a WOF check?

[Capt M Stubbing]

i put a crossply (by mistake) on my 1988 zx10, almost killed me. tank slapped something fierce. had crossplys on my vmax, thats all that fitted. was ok...if you like the handling like a vmax. i reckon one of the best improvements in bikes...is proper tyres.

[MarkH]

I know of someone (yes, they're a member on here) who asked a bike shop to get in a Pirelli Sport Demon (crossply) front tyre to match his rear tyre. The shop obviously never got around to ordering it and when the customer came in to get it fitted, they decided to fit a Metzeler M3 instead, simply because that was all they had in stock.

Did they advise this rider that they wished to fit a different tyre to what had been ordered? I would be unhappy if I ordered a tyre and took a bike in to have it fitted only to find the bike shop had forgotten to get the right tyre in and had just fitted what they had in stock. If I take a bike in to have a certain tyre fitted then that is what I expect them to do.

[boman]

always been told and have done, replace front and back at same time with matched tyres, if you chew back tyres out buy two and store reserve in back of garage, most probably will find better wear out of second trye as it has had time to cure properly.

Thats a bit of an old wives tale. Tyres nowdays are cured out of the mold. Keeping them stored usually makes the compounds start to harden, over a period of time. They might last longer but the grip can be reduced.

[Katman]

I would be unhappy if I ordered a tyre and took a bike in to have it fitted only to find the bike shop had forgotten to get the right tyre in and had just fitted what they had in stock.

That is precisely what happened.

Pirelli Sport Demon ordered to match Sport Demon on rear. (And told if Pirelli wasn't available than a BT45 would do).

Metzeler M3 (radial) fitted to front because they forgot to get the Pirelli in.

Their story was that the wholesaler was out of stock of the Pirelli. I can vouch for the fact that that was not the case.

[Pussy]

That is precisely what happened.
I'd be SPEWING if it happened to me.
Katman, this DOESN'T apply to your shop.... but this is yet another example of some bike shops doing themselves no favours

[Katman]

I'd be SPEWING if it happened to me.
Katman, this DOESN'T apply to your shop.... but this is yet another example of some bike shops doing themselves no favours

Absolutely.

I have put this matter out in the public view because I feel it is imperitive that shops are not allowed to get away with this sort of shoddy service.

New Zealand bike shops should not be attacked on the prices they charge for their goods (those prices are decided elsewhere) but if they fail to offer adequate service and, in consequence, compromise the safety of their customer then they should be taken to task over it.

[Pussy]

I 100% agree with you, Katman.
I have seen myself the attitudes displayed by a FEW shops.
Conversely, I have had great service from others, too.
Bike shops do not own the customer

[Mikkel]

The job of the front tyre is to force a 'dry' patch on the road for the rear to travel on. That only works in a straight line. At a lean, this is out the door, regardless of tread pattern.

Generally I'd expect that you would want the more capable (better grip in most situations) tyre to be on the front since that is where you do you braking and your steering....

I can't see how you would - in any imaginable case - "force a dry patch on the road for the rear to travel on" TBH. As you say it would work in a straight line only - and in a straight line it doesn't really matter too much...


You're already shown you don't know the first thing about tyres.

If it only was the bloody tyres mate... :no:


i put a crossply (by mistake) on my 1988 zx10, almost killed me. tank slapped something fierce. had crossplys on my vmax, thats all that fitted. was ok...if you like the handling like a vmax. i reckon one of the best improvements in bikes...is proper tyres.

1988 ZX10? Here I were to write something sarcastic - but it turns out I learned something today after all :)


That is precisely what happened.

Pirelli Sport Demon ordered to match Sport Demon on rear. (And told if Pirelli wasn't available than a BT45 would do).

Metzeler M3 (radial) fitted to front because they forgot to get the Pirelli in.

Their story was that the wholesaler was out of stock of the Pirelli. I can vouch for the fact that that was not the case.

So a Pirelli Sport demon isn't a radial? :scratch: I actually thought pretty much any tyre made today would be radial...


I have put this matter out in the public view because I feel it is imperitive that shops are not allowed to get away with this sort of shoddy service.

Indeed, tyres are "rather" important inside our shared passtime... Just out of curiosity, what shop was it? :Pokey:

[Jantar]

So a Pirelli Sport demon isn't a radial? :scratch: I actually thought pretty much any tyre made today would be radial...



There are still many older bikes out there with narrow rims and spoked wheels that benefit from crossply rather than radials. Katman has one, and I have another.

[Katman]

There are still many older bikes out there with narrow rims and spoked wheels that benefit from crossply rather than radials. Katman has one, and I have another.

"Benefit" may be stretching it.

:blink:

[Mikkel]

There are still many older bikes out there with narrow rims and spoked wheels that benefit from crossply rather than radials. Katman has one, and I have another.

In which way would a narrower rim benefit from a tyre manufactured with a, supposedly, less ideal construction method?

I am asking this in all seriousness, I quite simply don't know that much about other construction methods than radial.

[McDuck]

There are still many older bikes out there with narrow rims and spoked wheels that benefit from crossply rather than radials. Katman has one, and I have another.

And when you get a replica of a said bike that can take either the possibility becomes apparent.
One has to wounder how when there seems to be this knowledge out there how a bike shop can do this without thinking anything of it. It certainly dosnt help the biker who has to pick up the pieces...

[koba]

Are there radials and crossplys that will mix if mounting the tyre on the correct rim width?
All the bikes I have owned with cross plys wouldn't fit radials unles they were being jammed on an incorrect rim size...

[McDuck]

Are there radials and crossplys that will mix if mounting the tyre on the correct rim width?
All the bikes I have owned with cross plys wouldn't fit radials unles they were being jammed on an incorrect rim size...

Not that i know of (or at least not well) how ever i have herd of situations where the crossply as gone out of production and riders have run the risk of using a mix while changing over to a simmiler size...

[koba]

In which way would a narrower rim benefit from a tyre manufactured with a, supposedly, less ideal construction method?

I am asking this in all seriousness, I quite simply don't know that much about other construction methods than radial.

Crossplys work better with shit suspension or radials need better suspension to work correctly. (two ways of saying the same thing)
Radials tend to be built for wider rims/tyres.

If I put radials on my NC21 it would probably run worse.

I run sport demons at the moment.

Having experiance with both sport demons and BT45s IMO I would not say they are comparable, a Sport demon seems closer to a BT39.

[koba]

Not that i know of (or at least not well) how ever i have herd of situations where the crossply as gone out of production and riders have run the risk of using a mix while changing over to a simmiler size...

Can you get a 100 wide radial front or a 120 wide crossply front?

EDIT: Ah, My bad! I thought you were saying the opposite!
Time for more beer and battleships!

[McDuck]

Can you get a 100 wide radial front or a 120 wide crossply front?

Non spacific example. Could have been the other way round, could be anything

[Jantar]

In which way would a narrower rim benefit from a tyre manufactured with a, supposedly, less ideal construction method?

I am asking this in all seriousness, I quite simply don't know that much about other construction methods than radial.
It isn't so much a less ideal construction method as one that is designed for a different purpose. Radial tyres have more flex which allows more tread on the road and also allows the tyre to heat up to a more optimum temperature. Crossply tyres are generally stiffer and hold their shape more. Have a look at racing tyres of a couple of decades ago. They are crossply with an almost triangular profile so that there is more tread on the track when leaned over than when upright.

Also remember that most crossplys were desinged for spoked rims which means they must be fitted with a tube. Radials are generally designed to run tubeless.

[Jantar]

"Benefit" may be stretching it.

:blink:
See if you can find a set of crossplys as similar as possible to the old Pirelli Phantoms to put on that silver beast of yours. you'll be amazed at how quickly it will turn in and remain stable right through the turn.

[Mikkel]

It isn't so much a less ideal construction method as one that is designed for a different purpose. Radial tyres have more flex which allows more tread on the road and also allows the tyre to heat up to a more optimum temperature. Crossply tyres are generally stiffer and hold their shape more. Have a look at racing tyres of a couple of decades ago. They are crossply with an almost triangular profile so that there is more tread on the track when leaned over than when upright.

You must mean by cross-section - not area - surely...

[Katman]

Can you get a 100 wide radial front or a 120 wide crossply front?



The situation that McDuck is talking about is the one that a number of Ducati owners are now facing. The 906 Pasos and 750 Sports that ran a 160/60-16 rear have the problem that no tyre now exists in that size. Michelin used to be the only manufacturer that made a tyre in that size and they have recently discontinued making that tyre. Those owners now have to look at replacing their rear end with a 17" wheel (and the swing arm conversion that this entails) or going to a crossply of similar (but not very similar) dimensions (and then changing the front to a crossply when they need to).

[Jantar]

You must mean by cross-section - not area - surely...
I do indeed mean by area.

[Katman]

See if you can find a set of crossplys as similar as possible to the old Pirelli Phantoms to put on that silver beast of yours. you'll be amazed at how quickly it will turn in and remain stable right through the turn.

I am gutted that Pirelli are only putting out those Phantom replica tyres in 17".

[McDuck]

I am gutted that Pirelli are only putting out those Phantom replica tyres in 17".

Dose my 400 have 17s or 18s?

[Mikkel]

I do indeed mean by area.

I thought we had already agreed that vehicle weight and tyre pressure dictates the contact patch area :devil2:

[Chrislost]

I thought it was a no-no, as the biasply front and radial rear would cause massive understeer problems and the opposite would cause oversteer.

HOWEVER, this was ages ago and times change.

The Harley-Davidson Rocker runs a radial rear and a biasply front.

And they wouldn't sell anything that could be that dangerous given that they're from USA - the land of the law suit.

I dont think harleys can go fast enough or corner well enough for it to matter. (one would expect harley rear tyres are specially picked to work with harley front tyres!??!)

My workmate put a radial front and a bias ply rear on his Cb400. At about 160 his bike started to weave.
Still cornered fine.

[Ocean1]

I thought we had already agreed that vehicle weight and tyre pressure dictates the contact patch area :devil2:

You've contended that before.

You were wrong then also.

[Jantar]

I thought we had already agreed that vehicle weight and tyre pressure dictates the contact patch area :devil2:
With radial tyres that would be correct, less so with crossply.

[Katman]

Dose my 400 have 17s or 18s?

Well it clearly has a 17" front. That is the reason behind this whole thread. I don't know offhand whether the rear is 17" as well. If it turned out that the Pirelli Phantom repilcas fitted then they would be the absolute dog's bollocks!

[Mikkel]

You've contended that before.

You were wrong then also.

No, I wasn't.


With radial tyres that would be correct, less so with crossply.

How so?

[Ocean1]

No, I wasn't.

Were too.


How so?

You assume the tyre is a simple, completely non-rigid pressure barrier.

They're not.

[McDuck]

Well it clearly has a 17" front. That is the reason behind this whole thread. I don't know offhand whether the rear is 17" as well. If it turned out that the Pirelli Phantom repilcas fitted then they would be the absolute dog's bollocks!

Shit it is late, i think they are both 17''s.

Could be cool to have a set me thinks :headbang:

[Mikkel]

Were too.

Look, I already told you once... was not!


You assume the tyre is a simple, completely non-rigid pressure barrier.

They're not.

Please sexpand...

On the inside you have air at some pressure - on the outside you have air at @mosFEARic pressure and a road surface. Combined you need to provide some sort of physical equilibrium...

I agree that the tyre construction has an effect upon how the tyre, dynamically, adapts to fulfill this requirement. However, tyre profile, tyre pressure and vehicle weight and weight distributions are still what will dictate the contact patch area of each tyre.

[MarkH]

Pirelli Sport Demon ordered to match Sport Demon on rear. (And told if Pirelli wasn't available than a BT45 would do).

Metzeler M3 (radial) fitted to front because they forgot to get the Pirelli in.

Their story was that the wholesaler was out of stock of the Pirelli. I can vouch for the fact that that was not the case.

So he ordered a tyre, they didn't supply the tyre ordered, they lied about its availability and fitted something else? That is pretty fuckin' shitty IMO! He should tell them that he has been advised that the wholesaler was NOT out of stock and they should have supplied what he ordered and demand they replace the tyre!

Can anyone definitively state that there are handling issues with the tyre combination now on that motorcycle? I don't really know how the front radial combined with the rear cross-ply affects the handling. Regardless - he should have been supplied what he had asked for!

[Jantar]

How so?

OK, an extreme example. Take a trianglar block and and place it such that a corner is touching the ground. the contact area is very small, just the thickness of a line. Now lay it over onto an edge, and the contact area is very large. If this is the profile of a tyre then the same thing happens. A small contact area when upright and large when leant over. A radial tyre with a round profile will not change its contact area much at all.

The air inside the crossply tyre tyre is there to maintain the tyre shape and that is why crossply tyres are less susceptible to changes in tyre pressure than radials.

Even with radials the air pressure only has a small effect on contact area. Here's an experiment you can try for yourself, spread some flour or similar visible dust onto a smooth surface, take an old tyre and place it on the surface then remove it and measure the contact area. Remember relative air pressure is zero. Now repeat the experiment but place a weight equal to the tyre's weight on top of the tyre and remeasure the contact area. Has it doubled? I assure you it hasn't.

[McDuck]

So he ordered a tyre, they didn't supply the tyre ordered, they lied about its availability and fitted something else? That is pretty fuckin' shitty IMO! He should tell them that he has been advised that the wholesaler was NOT out of stock and they should have supplied what he ordered and demand they replace the tyre!


I belive the term used was a 'mix up (IE fuck up) and the M3 was suggested over the phone when (I) rang to conferm they had the tyre i wanted, they didnt have and the M3 was one the shelf.

[Ocean1]

Look, I already told you once... was not!


Was so.


I agree that the tyre construction has an effect upon how the tyre, dynamically, adapts to fulfill this requirement. However, tyre profile, tyre pressure and vehicle weight and weight distributions are still what will dictate the contact patch area of each tyre.

Oh, and tyre profile, now.

Add compound hardness and carcase structural characteristics and you'll have a reasonable picture.

And there's a substantial difference in those carcases, I believe that defines most of what we feel as difference between tyres.

[Mikkel]

OK, an extreme example. Take a trianglar block and and place it such that a corner is touching the ground. the contact area is very small, just the thickness of a line. Now lay it over onto an edge, and the contact area is very large. If this is the profile of a tyre then the same thing happens. A small contact area when upright and large when leant over. A radial tyre with a round profile will not change its contact area much at all.

You are correct, insofar that the tyre can be considered to be rigid... I have no experience with crossply tyres, but for radial tyres such a consideration is invalid...


Even with radials the air pressure only has a small effect on contact area. Here's an experiment you can try for yourself, spread some flour or similar visible dust onto a smooth surface, take an old tyre and place it on the surface then remove it and measure the contact area. Remember relative air pressure is zero. Now repeat the experiment but place a weight equal to the tyre's weight on top of the tyre and remeasure the contact area. Has it doubled? I assure you it hasn't.

So you suggest that the difference between 30 PSI and 15 PSI in a set of radial tyres is unimportant?

Your argument is flawed insofar that you assume that the rigid strength of a steel-belt reinforced rubber torus is zero...

The more valid experiment would consist of taking a tyre on a wheel and applying first 500 kg and then 1000 kgs to the axle and see what difference in contact patch area is observed. You will see an increase very close to 100% between measurement 1 and 2.

[Mikkel]

Was so.

Look, if you are just going to be difficult I'll have to send you off to bed early young man...


Oh, and tyre profile, now.

Add compound hardness and carcase structural characteristics and you'll have a reasonable picture.

And there's a substantial difference in those carcases, I believe that defines most of what we feel as difference between tyres.

I might be mistaken, but I actually thought that the compound characteristics changed throughout the tyre... If that is not the case, I would have to grant you that I might not have answered your query adequately in the post which I posted as a response to Jantar.

[Jantar]

You are correct, insofar that the tyre can be considered to be rigid... I have no experience with crossply tyres, but for radial tyres such a consideration is invalid...

No, I am not assuming that the tyre is rigid nor radial. I am saying that it is not perfectly elastic either. A crossply tyre is far more rigid when inflated than a radial tyre.



So you suggest that the difference between 30 PSI and 15 PSI in a set of radial tyres is unimportant?

Your argument is flawed insofar that you assume that the rigid strength of a steel-belt reinforced rubber torus is zero...

The more valid experiment would consist of taking a tyre on a wheel and applying first 500 kg and then 1000 kgs to the axle and see what difference in contact patch area is observed. You will see an increase very close to 100% between measurement 1 and 2.

If the weights you have suggested are within the tytre's rating then go ahead and try it. I would suggest that if you are going to use an inflated tyre, then measure its contact area with normal inflation and within its weight limits, then double the air pressure and remeasure. I thinkl you'll find that the decrease in contact area is around 50% for a radial tyre and around 10% for a crossply tyre.

[Mikkel]

If the weights you have suggested are within the tytre's rating then go ahead and try it. I would suggest that if you are going to use an inflated tyre, then measure its contact area with normal inflation and within its weight limits, then double the air pressure and remeasure. I thinkl you'll find that the decrease in contact area is around 50% for a radial tyre and around 10% for a crossply tyre.

Very interesting. I'll have to put it on my to-do-list, the chance of me owning a non-radial tyre within the foreseeable future is pretty close to nil.

So what is it, between radial and crossply construction, that causes this very considerable difference in mechanical rigidity?

[Jantar]

The name "crossply" may give a clue. The plys cross each other at an angle effectively giving a triangulation of the plys. It makes for a very rigid construction.

[Kickaha]

Also remember that most crossplys were desinged for spoked rims which means they must be fitted with a tube.

cross ply tyres have been available as tubless for years (if not decades)


I am gutted that Pirelli are only putting out those Phantom replica tyres in 17".

So am I:(



So what is it, between radial and crossply construction, that causes this very considerable difference in mechanical rigidity?

Belt angle, belt material blah blah blah

Car stuff but it should give you an idea
http://www.tyresite.com/tyrearticle.asp?page=11

Motorcyle related
http://books.google.co.nz/books?id=84hF-qoR5I8C&pg=PT69&lpg=PT69&dq=motorcycle+cross+ply+vs+radial+tyre+constructio n&source=bl&ots=FYz5yIP9Oh&sig=fJAh28mxOJ7U9YTgv1J2Rl2aKKk&hl=en&ei=ZiZiSs_oI4z0sQPx44Bn&sa=X&oi=book_result&ct=result&resnum=3

http://books.google.co.nz/books?id=l2Zizg8I8p8C&pg=PA37&lpg=PA37&dq=motorcycle+cross+ply+vs+radial+tyre+constructio n&source=bl&ots=Orc2ulihyD&sig=2sZRK18sbGj2_gf3pHdkg9-csYE&hl=en&ei=ZiZiSs_oI4z0sQPx44Bn&sa=X&oi=book_result&ct=result&resnum=7

[DEATH_INC.]

I belive the term used was a 'mix up (IE fuck up) and the M3 was suggested over the phone when (I) rang to conferm they had the tyre i wanted, they didnt have and the M3 was one the shelf.
There's two questions here, Did the custy 'ok' it before it was done (or ok it when the bike was collected), or not?
And of course, is it safe?
On a bike I don't think there'd be any massive safety issues (I've run them mixed, the turbo had a radial rear when I bought it) but I suggest that a quick e-mail to the tyre importer to get their view may be in order.
If it is legal and the customer said ok, then there is no issue.
If either is not the case then there's a big problem.
If the tyre manufacturer says it's ok, then the shop has done no real wrong, but should perhaps look a little at their service in the future...and perhaps the customer should consider a different tyre supplier....

[boman]

Here is a very basic diagram displaying the differences in the Two tyre types.

[ynot slow]

Pretty simple really,you ask(politely)can you grab me a tyre xyz size,if not can you suggest an alternative before you even place a replacement on the rim.The client should have the option of saying no sorry,that's not what I want.Not picking up the bike and finding something else is used.

Much like you go in and order a new Falcon XR8 GTP (after you've won lotto),upon arriving to pick up they hand you keys to a 1989 Mazda 626,they say well it is a Ford replica vehicle.

[MSTRS]

The correct recommendation on a car is radials to the rear


Dead horse, maybe, but I still don't remember it being that way...
(On a car) the tyre's sidewalls flex mightily in a corner. The tread on a crossply then peels up off the surface of the road, reducing the amount of grip. Whereas a radial keeps all the available tread on the road, maintaining the full amount of grip. Perhaps FWD/RWD makes a difference, but still seems to me that maintaining full potential grip is better at the front end?
Of course, none of this applies to bike tyres...(other than a rear-end slide is preferable to a front)

[koba]

I think the fact that there are a few pages of debate on the differences between crossplys and radials and all that show that KB isn't going to provide a crediable answer to Katmans initial question.

I'm sure you knew that when you asked it though...

I still wan't to know if there are radials that will fit on rims designed for crossplys.
I know 125 slicks will but thats not exactly a normal road tyre.

[McDuck]

There's two questions here, Did the custy 'ok' it before it was done (or ok it when the bike was collected), or not?
And of course, is it safe?


Was ok-ed over the phone after an assurance from the parts guy that it was a good tyre and would work well with the sport demon. As to saftey i am going by the fact that i went down on the first wet hill i had done on the combo, so i will go with no...

[Viscount Montgomery]

I'd say the 'yes or no' ply/radial mix scenario depends on the style of motorcycle, and there's always conjecture and statements of advice from people who think they know it all from scouring the net and reading manuals and rulebooks, but who have, at the end of the day, never actually ridden any motorcycle on a ply/radial combo. Now, I've run modern 17" 160/170 radials on the back of old modded musclebikes with the standard 100/110 width 19" ply tyre setup still on the front. Perfectly fucken safe, no handling dramas, fine scraping pegs on corners, stable and solid on hi-speed straightline blats, no unexpected slides in the wet, no uneven tyre wear. All under control and zero problems. Basically, just ignore the tut-tutting self-proclaimed experts and you'll be sweet.. PS, don't try fitting radials to too narrow ply-tyre rims, I squeezed a front 120/70 radial on to a standard ply 110 width rim just to see what would happen. The 120 radial distorted and turned to a 100 width with tall sidewalls - and turned from a stable tyre to a twitchy death-trap

[MarkH]

Was ok-ed over the phone after an assurance from the parts guy that it was a good tyre and would work well with the sport demon. As to saftey i am going by the fact that i went down on the first wet hill i had done on the combo, so i will go with no...

Have you E-Mailed the respective tyre manufacturers and/or motorcycle manufacturer to enquire about the safety of mixing those 2 tyres? If an expert could give you a definitive answer on this it would be worth presenting that info to the bike shop.

[koba]

OK, no one answered so I looked it up.

They do cross over in sizes but the radial do tend to be wider, especially on the rear.

[McDuck]

Have you E-Mailed the respective tyre manufacturers and/or motorcycle manufacturer to enquire about the safety of mixing those 2 tyres? If an expert could give you a definitive answer on this it would be worth presenting that info to the bike shop.

Not yet, will get on to it on monday ;) thanks

[Kokopelli]

For what it's worth, I currently have a radial Anakee on the front and a crossply Shinko on the rear of my R1150GS (dual sport tyres). The handling is not as good as with matched tyres, but so far nothing drastic has happened. I found a few dry patches today and have run them to the edge.

The GS sits like on rails when cornering and I've got wide handlebars. The story might be quite different on a twitchy sports bike. I also rarely go faster than 120 km/h, but then I usually don't slow down much for corners either.

On gravel it doesn't make and difference at all as far as I could tell. I won't mismatch again, but I am also in no hurry to change tires for the next few thousand km's.