Pirelli 200/60 vs Metzeler 190/60 diameter

[sharp2183]

Does anyone know the circumference or diameter figures for the Metzeler 190/60 slick and the Pirelli 200/60?

I'm wanting to make a change to the pirellis and need to determine what shock length adjustment is required.

Cheers!

[Bass]

Does anyone know the circumference or diameter figures for the Metzeler 190/60 slick and the Pirelli 200/60?

I'm wanting to make a change to the pirellis and need to determine what shock length adjustment is required.

Cheers!

My understanding is that the second figure gives the profile height as a % of the width, so the Pirelli would be 200 x0.6= 120 mm and the Metzeler is 190 x 0.6=114 mm.
So if that's correct then the Pirelli will be 2(200-114)=12mm greater in diameter than the Metzeler. Shock preload increase would be half of this or 6mm.
Wouldn't put my left one on this but I believe that it's the theory.
However, if you are using the same rim, then the Pirelli will not go out to its design width and so the profile will sit taller than designed. If that's the case, personally I would add another 2 mm to the preload.
You could calculate it roughly by assuming the Pirelli is a semicircle at 200 mm width and then working out the "height" of the semi-ellipse formed by squeezing it into 190mm, but that's just pedantic.

Just to really confuse you, do you have clearance issues? If not, why adjust the preload at all? If it has the correct static sag ATM, then changing tyre diameter does not alter that.

[sharp2183]

My understanding is that the second figure gives the profile height as a % of the width, so the Pirelli would be 200 x0.6= 120 mm and the Metzeler is 190 x 0.6=114 mm.
So if that's correct then the Pirelli will be 2(200-114)=12mm greater in diameter than the Metzeler. Shock preload increase would be half of this or 6mm.
Wouldn't put my left one on this but I believe that it's the theory.
However, if you are using the same rim, then the Pirelli will not go out to its design width and so the profile will sit taller than designed. If that's the case, personally I would add another 2 mm to the preload.
You could calculate it roughly by assuming the Pirelli is a semicircle at 200 mm width and then working out the "height" of the semi-ellipse formed by squeezing it into 190mm, but that's just pedantic.

Just to really confuse you, do you have clearance issues? If not, why adjust the preload at all? If it has the correct static sag ATM, then changing tyre diameter does not alter that.

Yes, if the theory is correct then I get the explanation. Hopefully the tyres are actually that width in reality.

There are no clearance issues and sag is correct for me. It is about ensuring I have the same geometry for handling and outright grip. It's set up very well for the 190/60. I would adjust with the shock length adjuster for ride height, not using preload. Sag would not be affected.

The 200/60 is also designed to go on the 6" rim right? So there should be no squeezing of the tyre more than it was designed to do right?

[Bass]

Yes, if the theory is correct then I get the explanation. Hopefully the tyres are actually that width in reality.

There are no clearance issues and sag is correct for me. It is about ensuring I have the same geometry for handling and outright grip. It's set up very well for the 190/60. I would adjust with the shock length adjuster for ride height, not using preload. Sag would not be affected.

The 200/60 is also designed to go on the 6" rim right? So there should be no squeezing of the tyre more than it was designed to do right?

OK, if I am reading this right, you want your steering head geometry the same and your rear shock setup the same. You propose to do this by screwing in the clevis on the end of the shock to compensate for the increase in rear tyre diameter???

I guess that your R6 (if that's the machine we are discussing) has a rising rate linkage on the rear suspension and therefore I think you have it pretty much nailed. Adjusting for ride height using preload is much faster and simpler but it would change where you are on the rising rate linkage curve.

As for the rim width that the tyre is designed for, I simply don't know. Can't help you there.

[sharp2183]

Sorry, I really should have given more info! The bike is an RSV4 running Bitubo suspension with a rear shock that has a shock length adjustment (a thread and nut) on the bottom of the shock. The rim size is 6", which is what the 190 and 200 is designed for.

Other than that yes I want to retain the existing settings/characteristics. Adding preload would change the sag which I don't want to do.

Anyway that is the idea, just need to know what the actual difference is between the two tyres.

[Bass]

Anyway that is the idea, just need to know what the actual difference is between the two tyres.


All good then.

[sharp2183]

All good then.

Cheers Bass, appreciate the help and info on how the section sizes work.

[Mental Trousers]

It ends up being a lot.

From memory I think I have to change the shock length by 6mm (like I said, it's a lot, so much I had to shell out for the extra long ride height adjuster) going from a 200 to a 190. That's on a 2005 CBR600RR.

The way I did it the first time was to measure the vertical distance from the ground through the centre of the rear axle to a point on the rear subframe (not the fairings cos you need somewhere solid) with one tyre. Changed tyre then measured again and adjusted the shock length to get back to the original figure. It's trial and error and you have to undo the shock linkage a couple of times but it's accurate enough. However, it's way easier than trying to do the math as you need to accurately measure a bunch of stuff that isn't easy to measure and using the 5.5 inch rim makes a balls up of the theory anyway.

I went from a 200 to a 190 and really don't want to go back again. The bike is so much nicer with the 190 and the gain in grip from the 200 is very marginal unless you're a riding god.

[sharp2183]

It ends up being a lot.

From memory I think I have to change the shock length by 6mm (like I said, it's a lot, so much I had to shell out for the extra long ride height adjuster) going from a 200 to a 190. That's on a 2005 CBR600RR.

The way I did it the first time was to measure the vertical distance from the ground through the centre of the rear axle to a point on the rear subframe (not the fairings cos you need somewhere solid) with one tyre. Changed tyre then measured again and adjusted the shock length to get back to the original figure. It's trial and error and you have to undo the shock linkage a couple of times but it's accurate enough. However, it's way easier than trying to do the math as you need to accurately measure a bunch of stuff that isn't easy to measure and using the 5.5 inch rim makes a balls up of the theory anyway.

I went from a 200 to a 190 and really don't want to go back again. The bike is so much nicer with the 190 and the gain in grip from the 200 is very marginal unless you're a riding god.

Awesome MT, thanks for the advice and the great idea.

I wonder if your experience was due to running on a 5.5" rim? Will be interesting to see as I love the 190 on the 1000 but the 200s were a good price and the reality is you don't know until you try!

Will give your method a shot.

[Mental Trousers]

Awesome MT, thanks for the advice and the great idea.

I wonder if your experience was due to running on a 5.5" rim? Will be interesting to see as I love the 190 on the 1000 but the 200s were a good price and the reality is you don't know until you try!

Will give your method a shot.

No worries.

I'll be surprised if you don't end up jacking the back end up a bit to get it to turn nicely again. The rotating mass of the 200 makes a heap of difference.

[sharp2183]

No worries.

I'll be surprised if you don't end up jacking the back end up a bit to get it to turn nicely again. The rotating mass of the 200 makes a heap of difference.

Jacking it up more? Wouldn't the change to the taller tyre be a significant change as is?

[Mental Trousers]

Jacking it up more? Wouldn't the change to the taller tyre be a significant change as is?

The way I outlined above means the entire chassis geometry stays the same. Same static sag, same rake/trail on the front etc. However, with the 200 in there the rotating mass has gone up so the rake/trail figures that worked with the 190 will be wrong for the 200. It'll be sluggish to turn so (after you've ridden it to confirm that) you'll most likely end up extending the shock a little to run less rake/trail to counter the larger rotating mass.

[sharp2183]

The way I outlined above means the entire chassis geometry stays the same. Same static sag, same rake/trail on the front etc. However, with the 200 in there the rotating mass has gone up so the rake/trail figures that worked with the 190 will be wrong for the 200. It'll be sluggish to turn so (after you've ridden it to confirm that) you'll most likely end up extending the shock a little to run less rake/trail to counter the larger rotating mass.

Makes perfect sense to me. I'll give it a whirl and find out!

[Shaun Harris]

Makes perfect sense to me. I'll give it a whirl and find out!



Just fit it and try it man, I doubt you will notice bugger all difference. Theories are one thing, true feel is another

[Mental Trousers]

Just fit it and try it man, I doubt you will notice bugger all difference. Theories are one thing, true feel is another

It makes a shit load of difference. I've gone back and forth between both 190 and 200 and there's always a loads of difference in the feel. It's not theory, it's actual "been there done that and here's why it works".

[sugilite]

Yeah, what Shaun says above. Tyres work differently on different bikes means you should just try it first, then make the call as to if you want to change the ride height etc.

[CHOPPA]

Like Shaun says just put it on. Wouldn't go adjusting ride height until you have tested it.

What compound did you get?

[sharp2183]

Like Shaun says just put it on. Wouldn't go adjusting ride height until you have tested it.

What compound did you get?

Sure, not hard to measure it in case but then try it as is first.

Got SC1s but have a uses SC0 to try too.

[manxkiwi]

However, if you are using the same rim, then the Pirelli will not go out to its design width and so the profile will sit taller than designed.

Many people think fitting a tyre on too narrow a rim will make it sit 'taller'. But the belts the tyre is made of are far too strong for this to happen. If it could do that, they'd balloon out like a dragster tyre at high speed. What actually happens is the profile is compromised. The diameter in the middle would be the same, but the mid points of the profile, either side would bulge out compared to where they were designed to be. Just sayin'.

[Bass]

Many people think fitting a tyre on too narrow a rim will make it sit 'taller'. But the belts the tyre is made of are far too strong for this to happen. If it could do that, they'd balloon out like a dragster tyre at high speed. What actually happens is the profile is compromised. The diameter in the middle would be the same, but the mid points of the profile, either side would bulge out compared to where they were designed to be. Just sayin'.


Good point - thanks for that.