dr_jekyll Posted January 21, 2009 Share Posted January 21, 2009 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 Quote Link to comment Share on other sites More sharing options...
miko_supra Posted January 21, 2009 Share Posted January 21, 2009 Interesting...Where do you work? Quote Link to comment Share on other sites More sharing options...
dr_jekyll Posted January 21, 2009 Author Share Posted January 21, 2009 I own a tyre garage , buisness is slow at the moment lol Quote Link to comment Share on other sites More sharing options...
bignum Posted January 21, 2009 Share Posted January 21, 2009 This is another reason supra`s on 19" wheels don`t handle, theres not enough tyrewall to absorb the initial shock/weight transfer. Quote Link to comment Share on other sites More sharing options...
Wez Posted January 21, 2009 Share Posted January 21, 2009 Isnt 28psi is a bit low? Quote Link to comment Share on other sites More sharing options...
supra matt Posted January 21, 2009 Share Posted January 21, 2009 To slow )Is 28 psi not a bit low? i was told your meant to run the factor pressure which is 36 psi all round . i was running 32 all round before i read the above , Quote Link to comment Share on other sites More sharing options...
Wez Posted January 21, 2009 Share Posted January 21, 2009 I run 34psi rear and 36psi front. Quote Link to comment Share on other sites More sharing options...
gaz1 Posted January 21, 2009 Share Posted January 21, 2009 i run 30 normal and 22 at the pod and still spin, i need some lessons as i heard you can teach old dogs new tricks:D Quote Link to comment Share on other sites More sharing options...
Homer Posted January 21, 2009 Share Posted January 21, 2009 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 Quote Link to comment Share on other sites More sharing options...
Steve Posted January 21, 2009 Share Posted January 21, 2009 I run 36 psi all round on my 19" wheels. Used the same pressures at Suprapod last year. Gripped rather well. Quote Link to comment Share on other sites More sharing options...
TRACIE_LOU Posted January 21, 2009 Share Posted January 21, 2009 12inchs of water blimey that would go above the exhaust lol Quote Link to comment Share on other sites More sharing options...
SteveR Posted January 21, 2009 Share Posted January 21, 2009 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? Quote Link to comment Share on other sites More sharing options...
merckx Posted January 21, 2009 Share Posted January 21, 2009 Surely that cannot be correct, voluntarily driving into 12 inches of water in any car would be stupid. It hardly simulates possible driving conditions. Was that meant to be 1 to 2 inches? Quote Link to comment Share on other sites More sharing options...
Ian C Posted January 21, 2009 Share Posted January 21, 2009 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 Quote Link to comment Share on other sites More sharing options...
dr_jekyll Posted January 21, 2009 Author Share Posted January 21, 2009 (edited) 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 January 21, 2009 by dr_jekyll (see edit history) Quote Link to comment Share on other sites More sharing options...
dr_jekyll Posted January 21, 2009 Author Share Posted January 21, 2009 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. Quote Link to comment Share on other sites More sharing options...
merckx Posted January 21, 2009 Share Posted January 21, 2009 sorry it was supposed to be 1/2 inch, 12 inches of water :D:D:D Quote Link to comment Share on other sites More sharing options...
SteveR Posted January 22, 2009 Share Posted January 22, 2009 Makes sense now Quote Link to comment Share on other sites More sharing options...
Luxluc Posted January 22, 2009 Share Posted January 22, 2009 12 inches of water :D:D:D Would be additional cooling for the FMIC :D I run 265-30 19 rear and 235-35 19 front. What would be a fine pressure for road and track? Quote Link to comment Share on other sites More sharing options...
Jellybean Posted January 22, 2009 Share Posted January 22, 2009 (edited) 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 January 22, 2009 by Jellybean (see edit history) Quote Link to comment Share on other sites More sharing options...
Luxluc Posted January 22, 2009 Share Posted January 22, 2009 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 Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted January 22, 2009 Share Posted January 22, 2009 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. Quote Link to comment Share on other sites More sharing options...
Jellybean Posted January 22, 2009 Share Posted January 22, 2009 I think in around 32/33 might be the correct choice, I will try Front *36* Rear *34* and if its crap will try 32/32 and 33/33 Hopefully should get a happy medium Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 22, 2009 Share Posted January 22, 2009 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 Quote Link to comment Share on other sites More sharing options...
Jellybean Posted January 22, 2009 Share Posted January 22, 2009 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 Quote Link to comment Share on other sites More sharing options...
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