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tyre and grip research


dr_jekyll
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as with most supras i and a friend have problems with rear end grip so i have spent all day at my workshop testing different setups for rear tyres.

 

Previously i have had 295/30/18s on the back bu hiting boost in 2nd and third would trow the rear all over the place and off the mark was embarresing ontop of that any kind of standing water ment instant aquaplaing . the tests wer conducted using all pirelli p zero rosso tyres .

 

first we tryed the conventional 265/35/18 and found at 50mph hiting 12inch of standing water was a lot more stable than the 295s. but the accelaration was still a problm. after tryin 255s 275s and 285s we decided to move to a 40 profile wall and the difrence was instant , running a 265/40/18 at 28psi the car bites initialy with less spin and ther was nearly no spin at the gear changes through 2nd and 3rd ,

 

so if anybody is suffering for rear end grip try a slighly bigger wall I recomennd a 264/40/18 and 28psi and you will see a noticeable difference ,

 

this test was only usefull for 18inch rims , the front tyres were 235/40/18 on throughout ,

 

this is how i pass my day , hope its usefull to somebody

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I run 34psi rear and 36psi front.

 

Same here Wes for road and track days, but thats on 17's. At pod I found the best grip was found at 20psi on the rears.

 

I also found that moving to 18's with a wider tyre and lower profile really impacted the grip and handling, especially on exiting from the corners, the narrower 17's gave far more traction and control. That said I'm not expert on track days so might just be a lack of skill & experience :D

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Probably 1/2"

 

I run 28psi in the back tyres, it stopped the middle band wearing out faster than the edges. 34psi up front stopped the inner edges wearing out fast. I run Pirelli P0's as well, in 265/35 form though. Nice to know they are fairly sensible. Chris Wilson always said you could over-tyre a car and adversely affect the handling.

 

-Ian

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I'm confused, what is "12 inches of standing water"? 12" deep?! You drive into a pond?! ;)

Also, what has water displacement (which, TBH I thought would get worse with wider tyres - surely??) got to do with dry road grip?

 

sorry it was supposed to be 1/2 inch,

i have tryed many brands of tyre and i find the pirelli to be the best allrounder in terms of performance to wear rate. 28 psi is a bit softer than is reccomended but ther is alot more bite than at 36psi

Edited by dr_jekyll (see edit history)
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I'm confused, what is "12 inches of standing water"? 12" deep?! You drive into a pond?! ;)

Also, what has water displacement (which, TBH I thought would get worse with wider tyres - surely??) got to do with dry road grip?

 

yes wider tyres are worse on standing water , that was my reason for dropping to a 265, 295swould be better in dry conditiond but im looking for the best copramise for the road in all conditions.

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I Run

 

235-35 19 up Front

275-35 19 Rear

 

I tried these Tyre pressures for a min of 3-4 weeks

 

Front 30 --

Rear 28

 

OutCome -- Found car didnt handle too good,she didnt feel planted in the corners. She had loads of grip but I ran this during the Summer.

 

Summary -- She felt stable when going fast, but wasnt planted through corners especially via roundabout changing Direction quickly similar to a chicane

 

Front 32 --

Rear 30

 

OutCome -- Found car didnt handle too good,she didnt fell planted in the corners. She seemed to lack grip when on boost especially during the winter (Damp conditions)

 

Summary -- She felt stable when going fast, but wasnt planted through corners especially via roundabout changing Direction quickly similar to a chicane. She did soak up bumps better

 

Front 34

Rear 32

 

 

OutCome -- Found car handles better,soaks up bumps better, more responsive to steering input and feels more planted in the corners but not still happy. She has lack grip when on boost especially during the winter But it is a noticeable percentage better than before.

 

Summary -- She doesnt feel as stable when going fast, but better planted through cornors especially via roundabout changing Direction quickly similar to a chicane

 

 

I will try

 

Front 36

Rear 34 next and after

 

Front 36

Rear 36

Edited by Jellybean (see edit history)
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I Run

 

235-35 19 up Front

275-35 19 Rear

 

I tried these Tyre pressures for a min of 3-4 weeks

 

Front 30 --

Rear 28

 

OutCome -- Found car didnt handle too good,she didnt feel planted in the corners. She had loads of grip but I ran this during the Summer.

 

Summary -- She felt stable when going fast, but wasnt planted through corners especially via roundabout changing Direction quickly similar to a chicane

 

Front 32 --

Rear 30

 

OutCome -- Found car didnt handle too good,she didnt fell planted in the corners. She seemed to lack grip when on boost especially during the winter (Damp conditions)

 

Summary -- She felt stable when going fast, but wasnt planted through corners especially via roundabout changing Direction quickly similar to a chicane. She did soak up bumps better

 

Front 34

Rear 32

 

 

OutCome -- Found car handles better,soaks up bumps better, more responsive to steering input and feels more planted in the corners but not still happy. She has lack grip when on boost especially during the winter But it is a noticeable percentage better than before.

 

Summary -- She doesnt feel as stable when going fast, but better planted through cornors especially via roundabout changing Direction quickly similar to a chicane

 

 

I will try

 

Front 36

Rear 34 next and after

 

Front 36

Rear 36

 

Nice comment :thumbs:

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I Run

 

235-35 19 up Front

275-35 19 Rear

 

I tried these Tyre pressures for a min of 3-4 weeks

 

Front 30 --

Rear 28

 

OutCome -- Found car didnt handle too good,she didnt feel planted in the corners. She had loads of grip but I ran this during the Summer.

 

Summary -- She felt stable when going fast, but wasnt planted through corners especially via roundabout changing Direction quickly similar to a chicane

 

Front 32 --

Rear 30

 

OutCome -- Found car didnt handle too good,she didnt fell planted in the corners. She seemed to lack grip when on boost especially during the winter (Damp conditions)

 

Summary -- She felt stable when going fast, but wasnt planted through corners especially via roundabout changing Direction quickly similar to a chicane. She did soak up bumps better

 

Front 34

Rear 32

 

 

OutCome -- Found car handles better,soaks up bumps better, more responsive to steering input and feels more planted in the corners but not still happy. She has lack grip when on boost especially during the winter But it is a noticeable percentage better than before.

 

Summary -- She doesnt feel as stable when going fast, but better planted through cornors especially via roundabout changing Direction quickly similar to a chicane

 

 

I will try

 

Front 36

Rear 34 next and after

 

Front 36

Rear 36

 

 

On my old UK spec, I used to run the same size wheels and tyres (Even using 35 profile rear tyres instead of the recommended 30) and I ran front and rears at 32psi. The tyres where Toyo T1Rs. I found it gripped really well in the dry and even quick steering inputs felt completely stable.

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Stick it on 16 inch rims and narrow rubber if you want awesome wet handling, been saying over tyreing a MKIV is a disaster for road use for God knows how long, but style seems more important than grip to most owners these days ;)

 

On 16 inch Rims my bumper will last all of 3 meters on Irish roads ;)

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