Raising the old tyre size debate, with apologies

[Angrybird]

Sorry for thrashing an old topic. I have decided on Dunlop Sportsmarts for my ZX14 and was tossing up between the 190 55s and the 190 50s. I like the idea of more tyre on the road when leaned over but by the same token I don't really want to raise my ride height by 14.5mm or up the gearing. The 180 55 would seem to have been ideal from a gearing and ride height standpoint but I had steered clear (no pun intended) of them as my tyre guy said that you need to stretch them to fit a 6 inch rim thus defeating their purposes. Then I read this, "FYI you are not 'stretching' the tire onto the rim when using a 180 on a 6" wheel." I would be most grateful if anyone can clarify this with specific regard to the Sportsmarts.

[DMNTD:Me]

Sorry for thrashing an old topic. I have decided on Dunlop Sportsmarts for my ZX14 and was tossing up between the 190 55s and the 190 50s. I like the idea of more tyre on the road when leaned over but by the same token I don't really want to raise my ride height by 14.5mm or up the gearing. The 180 55 would seem to have been ideal from a gearing and ride height standpoint but I had steered clear (no pun intended) of them as my tyre guy said that you need to stretch them to fit a 6 inch rim thus defeating their purposes. Then I read this, "FYI you are not 'stretching' the tire onto the rim when using a 180 on a 6" wheel." I would be most grateful if anyone can clarify this with specific regard to the Sportsmarts.

Can't comment on those specific tyres with a ZX14, but I do recommend the change to a 190/55 on a ZX14....no question IMO

[Drew]

Not enough information.

Without knowing what type of riding you do it's not really possible to comment either way.

[sinfull]

between the 190 55s and the 190 50s. I like the idea of more tyre on the road when leaned over but by the same token I don't really want to raise my ride height by 14.5mm or up the gearing.

Reading that, it strikes me you think that the different profiles will change your ride height by how much ?

The 180 55 would seem to have been ideal from a gearing and ride height standpoint but I had steered clear (no pun intended) of them as my tyre guy said that you need to stretch them to fit a 6 inch rim thus defeating their purposes. Then I read this, "FYI you are not 'stretching' the tire onto the rim when using a 180 on a 6" wheel." I would be most grateful if anyone can clarify this with specific regard to the Sportsmarts.

See if ya can get a picture in ya head, put palms and fingers together and then start opening your palms to 6 inches apart, now have your fingers make an even curve, then force them another 2 inches apart, the fingers are how the curvature of the tyre will look, the back of ya hands is now what the tyre walls will look like on the rim

Do you think the narrower tyre (180) will look rather flat on a wide rim ? thus losing any lean you may want in some corners ?

Can be done if ya like going in straight lines only, but the tyres differ in wall strength and there is the possibility of rolling the wall off the rim if it's on too much of an angle (backs of ya hands) more so spooning a 190 on to a 5 inch rim but hey !

The 190 is the way to go, I'd go the 55 but don't think it really makes SFA difference (ie like 5mm profile) I might be corrected on that lol

[Haggis2]

I'd be inclined to stick with standard sizes, the manufacurers surely put a lot of time into making sure they have the best possible size to bridge all uses. Just my thoughts though

[Drew]

I'd be inclined to stick with standard sizes, the manufacurers surely put a lot of time into making sure they have the best possible size to bridge all uses. Just my thoughts though

But, he might not ride it the way the manufacturer intended either. He might have stumpy arms and long legs, throwing the weight distribution well away from kawasaki's test models.

If you ride feisty roads heaps, get the 55. If not, get the 50.

KISS. Keep it simple, stupid.

[Angrybird]

Can't comment on those specific tyres, but I do recommend the change to a 190/55 on a ZX14....no question IMO

Thanks for that DMNTD. Being that it is a large bike I am coming back to the thought that it would benefit from the larger contact patch afforded by the 190 55s cf the 180 55s.

[slowpoke]

But, he might not ride it the way the manufacturer intended either. He might have stumpy arms and long legs, throwing the weight distribution well away from kawasaki's test models.

If you ride feisty roads heaps, get the 55. If not, get the 50.

KISS. Keep it simple, stupid.

Thanks for that DMNTD. Being that it is a large bike I am coming back to the thought that it would benefit from the larger contact patch afforded by the 190 55s cf the 180 55s.

Drew's on the money here. It's not just about contact patch, it's about the shape of the tyre and the extra agility the taller profile gives. I farkin' hate the way the 50's seem to make everything much harder work compared to the much sweeter steering 55, but each to their own.

[Angrybird]

Reading that, it strikes me you think that the different profiles will change your ride height by how much ?



See if ya can get a picture in ya head, put palms and fingers together and then start opening your palms to 6 inches apart, now have your fingers make an even curve, then force them another 2 inches apart, the fingers are how the curvature of the tyre will look, the back of ya hands is now what the tyre walls will look like on the rim

Do you think the narrower tyre (180) will look rather flat on a wide rim ? thus losing any lean you may want in some corners ?

Can be done if ya like going in straight lines only, but the tyres differ in wall strength and there is the possibility of rolling the wall off the rim if it's on too much of an angle (backs of ya hands) more so spooning a 190 on to a 5 inch rim but hey !

The 190 is the way to go, I'd go the 55 but don't think it really makes SFA difference (ie like 5mm profile) I might be corrected on that lol

Thanks sinfull. Going back to my calculator 5% of 190 (ie 55% v 50%) is 9.5mm (not 14.5mm). Even allowing for a bit of squishing of the extra rubber I still see an increased ride height of around 9mm. Hoping to find an exact measurement I emailed Dunlop NZ asking for Sportsmart diameter measurements but have heard nothing back.

On top of the static measurement tyres also get bigger when they spin (watch the top fuel dragsters) and so the ride height should increase beyond the 9mm when the bike gets up to speed. Not sure of the merits of adding sag to maintain the steering geometry.

The point you made is exactly the way I had come to see the issue of 180 v 190 tyres. The poster I quoted on the subject of "stretching" disputed this and I even found a quote from Dunlop's website which recommended (180 55s?) for 6 inch rims.

That sounded dubious to me. As you pointed out the profile of a given 180 must differ between a 5.5 and 6 inch rim. Surely they have optimised it for one or the other. Indeed when they are quoting the profile heights it must be per a given rim size therefore? But no they just bandy around numbers in the way Aiwa quoted wattage for their ghetto blasters.

I found many subjective comments in favour of both but nothing to say a 180 on a 6" rim is a categoric "no-go." Some highly technical types had actually found a way of measuring maximum theoretical lean angles. If manufacturers were to supply this info in respect of the tyre when fitted to the rims for which it was recommended that might be helpful.

[jrandom]

190/55s are sweet, and they'd make any bike nicer to ride around corners, I suspect. But if you do a lot of motorway pootling they won't last long, because they'll square that pointy middle straight down to the belt in no time flat.

If you ride feisty roads heaps, get the 55. If not, get the 50.

^ wot 'e said.

[jrandom]

Thanks sinfull. Going back to my calculator 5% of 190 (ie 55% v 50%) is 9.5mm (not 14.5mm). Even allowing for a bit of squishing of the extra rubber I still see an increased ride height of around 9mm. Hoping to find an exact measurement I emailed Dunlop NZ asking for Sportsmart diameter measurements but have heard nothing back.

Jesus H Christ, you're a bit of a fucking Poindexter, aren't you?

[Angrybird]

I'd be inclined to stick with standard sizes, the manufacturers surely put a lot of time into making sure they have the best possible size to bridge all uses. Just my thoughts though

Hi Haggis. Good point. Somewhere in my reading a comment stood out about "strafing an offramp" as if it were the poster's justification for his heavy outlay on the latest and greatest Pirelli Supercorsas.
With all the tough talk you see in American forums you have to wonder how much of that is compensatory. How many of them are as good as the descriptions of their knee/elbow/head-dragging exploits would suggest and how many of them spend most of their riding hours droning away at freeway velocity?

I also found another comment by an authoritative sounding poster who described the standard 190 50s as crap. Got me thinking that this was a manufacturer's catchall for those who run up big numbers commuting on said freeways. America after all must be one of the biggest motorcycle consumers if not the biggest.

We live in New Zealand however where only the major centres have the luxury of straight-lining motorways. I believe that a tyre optimised for corners would therefore be more appropriate as standard fare for the New Zealand market.

[Angrybird]

Drew's on the money here. It's not just about contact patch, it's about the shape of the tyre and the extra agility the taller profile gives. I farkin' hate the way the 50's seem to make everything much harder work compared to the much sweeter steering 55, but each to their own.

Thanks slow-poke. These days I am finding my way on motorcycles closer to 200 horsepower than the featherweight 39hp RD350 I cut my teeth on in the seventies and everything has changed. Back then I would just throw it. I have memories of scraping up loose chips with my footpegs on a melting Waioeka Gorge road and couldn't see anything wrong with the picture. These days I am not so sure.

Accordingly I am taking myself back to school with a view to learning all the new rules. With my Fireblade on 190 55s I have the sense of having to fight it to really get it over in a corner and it doesn't feel natural. The Dunlop TT100s on my little Yamaha were virtual triangles and the bike was as happy on it's side as it was vertical.

I am starting to think that one of my new rules should be, "Don't blindly follow along with what the manufacturer says." I thought the 190 50s are hard work and I take your comment as validation. How it translates to the ZX is a different story. At least having a 190 50 and 190 55 I would have the option of swapping.

[Angrybird]

Jesus H Christ, you're a bit of a fucking Poindexter, aren't you?

Cheers J Random.. meet M Specific. :-)

[Angrybird]

But, he might not ride it the way the manufacturer intended either. He might have stumpy arms and long legs, throwing the weight distribution well away from kawasaki's test models.

If you ride feisty roads heaps, get the 55. If not, get the 50.

KISS. Keep it simple, stupid.

Apologies drew.. I am getting to ewe. (Saving the best to larst :-) Thanks for all your thoughts. Nope arms aren't stumpy.. my wingspan is longer than Michael Phelps. Still not long enough to allow me to sit upright on my ZX. Yep I ride feisty roads.. Can you spell Gizbun Eest Khost? :-)