Slicks - tyre pressures?
Discussion
I've got a well set up (non road legal) BMW E36 328 Coupe with full roll cage and rose jointed adjustable suspension. Whilst doing a track day at Brands Hatch Indy circuit last week I was getting understeer exiting Druids when the tyres were hot. I run the pressures 38 front and 36 rear (18" wheels) and don't normally have understeer problems on other circuits.
When I spoke to Toyo at the Festival of Speed their tyre expert reckoned I should run 34 all round but I have found 38/36 is usually about right.
Should I increase the front tyre pressure or decrease it to help prevent/reduce understeer in tight corners such as Druids?
When I spoke to Toyo at the Festival of Speed their tyre expert reckoned I should run 34 all round but I have found 38/36 is usually about right.
Should I increase the front tyre pressure or decrease it to help prevent/reduce understeer in tight corners such as Druids?
'cold' pressures are essentially irrelevant unless you know what 'hot' pressure they equate to.
Losing grip when hot suggests your front pressures are too high. Next time you're on track, do a hot session then immediately pit and check your hot pressures, equalising them across the axles and reducing them if you feel they're going off. Once they're cool you'll probably find that you've got LF 34 RF 35 LR 36 RR 37 I.e. unequal cold pressures which equalise once the tyres are hot.
P.S. All of the pressures you mention seem a little high to me, then again I have no slicks experience- did the Toyo guy mean 34 hot or 34 cold? Are you talking hot or cold pressures?
Losing grip when hot suggests your front pressures are too high. Next time you're on track, do a hot session then immediately pit and check your hot pressures, equalising them across the axles and reducing them if you feel they're going off. Once they're cool you'll probably find that you've got LF 34 RF 35 LR 36 RR 37 I.e. unequal cold pressures which equalise once the tyres are hot.
P.S. All of the pressures you mention seem a little high to me, then again I have no slicks experience- did the Toyo guy mean 34 hot or 34 cold? Are you talking hot or cold pressures?
Edited by HustleRussell on Thursday 27th September 19:32
Rather than giving you meaningless generalisations, Toyo should give you the temps that their tyre's construction and rubber grade performs best at - they should know, afterall, they designed, specced and made them! Get those (including gradient from inner to middle to outer edges), then get yourself a proper surface penetrative tyre temperature gauge and away you go - in a playful but but better informed way; not only pressures, but also such as camber and toe; it very much depends on the car (and the track and the conditions); for example, on our aero car we aim to run 22psi F&R hot so, the variables mean it can start at anything from about 15 - 19psi cold, perhaps a little higher when on wets (hand-cut slicks).
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