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The mkiv Supra Owners Club

Tyre profile choices


berg

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Im changing my wheels back down to 18's now and have been looking at tyres

 

Main reason is now my single is all set up i want to try and maximise traction so the idea of a smaller wheel and larger profile seems to make sense

 

Im just trying to find out why the premium type tyres like R888, AD08R etc only seem to offer a 30 profile for anything wider than a 275?

 

Im trying to get the best size tyre i can but for me the optimum profiles for 18's on a supra would be a 40 profile up front, and a 35 on the rear, where as the 30 profile at the back seems more suited for a 19" wheel

 

After looking at the AD08R the 255 offer a 40 profile, but 285 and 295 only come as 30 which doesnt seem like it will match very well

 

Would there be any real benefits going from a 235/35/19 & 275/30/19 over to a 255/35/18 & 295/30/18?

 

I know they are wider but wider doesnt always mean better traction and from my understanding the profile plays a massive part in traction so i dont get why these top tyres dont seem to offer more choice, i know width also affects the profile size too which may answer my question :think: :confused:

Edited by berg (see edit history)
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The profile is a percentage of the width, so a 30 profile on a 315 is going to give a larger sidewall than a 30 profile on a 265/275 etc. In fact, a 315/30 has a bigger sidewall (94.5mm) than a 265/35 (92.75mm).

 

A benefit of dropping to an 18" would be that you could get more sidewall in there due to losing 1" diameter on the rim. 275/30/19 is only 0.4" smaller than 285/35/18 for example. A 295/30/18 would give a bigger sidewall, bigger width and more arch clearance due to being smaller in diameter. The tyres are probably cheaper too. :)

 

I run a 295/30/18 R888 on the rear just now and don't have any traction issues whatsoever. :thumbs:

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Currently running:

 

front: 8.5jx18 235/40/18

 

rear: 9.5jx18 275/40/18

 

Only had them on for a few weeks, but pretty convinced this is the best compromise for a road car. No noticeable downsides over the 35, but the ride quality on the rear of the car is much improved. Need to check my speedo still though to check how accurate it is now, although I'm expecting some leeway as it read too low before.

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go for a Jamie Fosta style mate, drag wheels on the rear... I'm tempted with that mainly for the ride quality. My 19s are on a 30 profile, you can feel it :(

 

Supra's with 30's on 19's have ride quality comparable to a Fakir's bed.

 

40's on 18's is as low a profile that works properly on a Supra.

Edited by David P (see edit history)
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Supra's with 30's on 19's have ride quality comparable to a Fakir's bed.

 

40's on 18's is as low a profile that works properly on a Supra.

 

40's may be more comfortable, but using a 255 width tyre as an example, 35's on an 18 are practically identical to the 17''/40/255's that left the factory.

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Your rationale being?

 

The squidge of a tyre is an essential activity for suspension designed to use it, without this squidge the suspension cannot work properly and will crash along like a Fakir's bed increasing the odds of finding a ditch.

 

If you won't believe me, try believing Chris Wilson. :shrug:

Edited by David P (see edit history)
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The squidge of a tyre is an essential activity for suspension designed to use it, without this squidge the suspension cannot work properly and can/will crash along like a Fakir's bed.

 

If you won't believe me, try believing Chris Wilson. :shrug:

 

I believe both you and Chris Wilson, but would like to state my car feels as refined and comfortable as a ponies ass on the existing setup. :)

 

 

 

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The squidge of a tyre is an essential activity for suspension designed to use it, without this squidge the suspension cannot work properly and will crash along like a Fakir's bed increasing the odds of finding a ditch.

 

If you won't believe me, try believing Chris Wilson. :shrug:

 

The squidge of a tyre is an essential activity for suspension designed to use it, without this squidge the suspension cannot work properly and will crash along like a Fakir's bed increasing the odds of finding a ditch.

 

If you won't believe me, try believing Chris Wilson. :shrug:

 

I'm sorry but that's BS. I've run everything from 45's down to 30's on my supra, and the only negatives I can list are increased harshness over bumps and less grip in the wet/cold.

 

From what I've experienced, the 30's I had were a little much for day to day travel, but worked great on the track. The 45's I used were terrible for anything but sedate driving. I could feel the sidewalls flexing when pushing it through the corners. Not great for inspiring confidence, especially as Supra is a heavy car that likes to understeer from the factory.

 

I'd rather sacrifice some road comfort and the loose stock handling feel for more grip and a stiffer ride.

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You cant paint all tyres with the same brush regarding sizes though.

The profile size is a percentage of the width.. therefore a 295 30 18 wont have the same side wall depth as a 225 30 18 thus making your coment completely redundant?

I may be wrong here and i dont claim to be any sort of tyre size genius but i dont understand how you can say 30 profile tyres are bad without also stating a width?

 

 

 

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