Tyre Width And Grip

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Discussion

redgriff500

Original Poster:

26,919 posts

264 months

Saturday 31st October 2009
quotequote all
I am aware that by increasing tyre width from say 195 to 225 will change the shape of the contact patch on the road.

But is there any quick and easy formula to work out what it will actually do regarding grip levels - both whilst cornering and on acceleration.

(Assuming the same type of tyre)

IIRC it won't improve cornering speeds but will improve grip upon acceleration thus reducing wheelspin but by how much ?


redgriff500

Original Poster:

26,919 posts

264 months

Sunday 1st November 2009
quotequote all
I'm increasing the power of a RWD car from 130bhp to 250bhp, torque is more than doubling to 260ftlbs.

Std is 195's on a 6" rim I was thinking of going to 225 on a 7 or 8" rim.

It has an LSD but no electronic aids will be fitted.


redgriff500

Original Poster:

26,919 posts

264 months

Sunday 1st November 2009
quotequote all
Approx 1150kg pretty much 50:50 distribution.

redgriff500

Original Poster:

26,919 posts

264 months

Sunday 1st November 2009
quotequote all
Yes 195 front and 225 rear was what I was thinking really (for no particular reason other than it seemed right and TVR's with similar power run 225's yet my car tramlines terribly with more than 195's on the front)

Saaby93 - I read that which is pretty much what I remembered except I thought that with the wider contact patch (ie involving more road surface) meant better grip for acceleration / braking which he doesn't seem to cover.

Also he mentions wider tyres have a better slip angle due to the lower profile but mine will effectively have the same profile (in height albeit a lower percentage, say 225/40/15) as I want to keep the wheel size and rolling radius similar.

redgriff500

Original Poster:

26,919 posts

264 months

Sunday 1st November 2009
quotequote all
Having read all this...

The obvious question is:

Why do Supercars run 345's etc when they aren't that heavy, is it just fashion ?

And surely drag racers would opt for the best size available as every 100th counts and they tend to be pretty wide !

Edited by redgriff500 on Sunday 1st November 14:08

redgriff500

Original Poster:

26,919 posts

264 months

Tuesday 3rd November 2009
quotequote all
redgriff500 said:
Having read all this...

The obvious question is:

Why do Supercars run 345's etc when they aren't that heavy, is it just fashion ?

And surely drag racers would opt for the best size available as every 100th counts and they tend to be pretty wide !
Anyone ?