tyre pressures
Discussion
verminator said:
Could some kind soul tell me the correct tyre
pressures for a cerb with 18" spiders and
toyos? I was told by the dealer they are the
same as standard wheels and tyres is this right?
Thanks for the info. Might drive up to dunton green
tonight to the meet, just to road test the tyres of
course, well thats what i will tell the missus.
Tripps said:
Thanks for the info. Might drive up to dunton green
tonight to the meet, just to road test the tyres of
course, well thats what i will tell the missus.Hopefully see you later.
Rob...I wont be across tonight....got a s#it load of paperwork to do, and besides weather looks crap!
[quote=SXS ]Lower the pressures for cold/icy days... and increase for warm to hot... would be nice to have dynamically adjusting air pressure according to ambient temperatures... (hint: joolz, another one for the future upgrades list! do it already man!)[/quote]
Pardon my ignorance but pressure falls with a drop in temp and rises as things heat. Why lower on a cold day and raise on a hot one? Maybe I need to hit the old physics books again...
Pardon my ignorance but pressure falls with a drop in temp and rises as things heat. Why lower on a cold day and raise on a hot one? Maybe I need to hit the old physics books again...
spslward said:Pardon my ignorance but pressure falls with a drop in temp and rises as things heat. Why lower on a cold day and raise on a hot one? Maybe I need to hit the old physics books again...[/quote]I was wondering about this, but you're told to raise the temps by a few psi for trackdays, presumably to make the tyres stiffer and deform less and when stuck on snow/sand you're told to almost complete deflate tyres for a greater surface area to spread the cars load over...
[quote=SXS ]Lower the pressures for cold/icy days... and increase for warm to hot... would be nice to have dynamically adjusting air pressure according to ambient temperatures... (hint: joolz, another one for the future upgrades list! do it already man!)
Perhaps thats it?
SXS said:
Great tyres too... problem is, different tyres and sizes will mean different psi to work optimally... sadly theres no psi that fits all....
I tend to find 0 PSI works best on Bridgestone S03s. Makes it much easier to take the pieces of crap off and replace them with something that doesn't tramline, works in the wet, doesn't need 3000 miles to be run in properly, etc. etc. etc.
Although, to be fair, since I've switched them to the back and put the F1s on the front, they're not upsetting me any more.
spslward said:
Pardon my ignorance but pressure falls with a drop in temp and rises as things heat. Why lower on a cold day and raise on a hot one? Maybe I need to hit the old physics books again...
Sarky or what!
Your physics is spot on. But you forget friction, traction, rubber compound elasticity, rate of heat increase, weight distribution and contact patch... These are also physics related theories... you have to apply all to understand car dynamics and handling... I've got all the words, from all over the net, from expert opinions, right down to software which assist in getting it right (must admit, some of the numbers go over my head)...
but the final word is always try it, learn from the mistake, keep doing it with different settings, until you see a pattern form, sooner or later you will hit 'eureka'!...
SXS said:
Although, to be fair, since I've switched them to the back and put the F1s on the front, they're not upsetting me any more.
GDS3's right? Hehe, thats my setup! It works well doesnt it!
It's not bad. F1s definitely suit the front - very precise on the turn-in, whereas the S03s always seemed to be playing catch-up to initial movements (not to mention the rest of the awful habits they had).
When the Bridgestones wear out on the rear, I'd actually quite like to stick P-Zeros on the back (need to figure out exactly which ones yet). Used to run P-Zeros rear and S02s front on my Elise, and it took a LOT of sets of tyres to come up with that match.
spslward said:
Easy fella...wasn't meant to be 'sarky'!!!!
I was just pointing out that for a muggins like me, overinflating on a hot day and underinflating on a cold day seems strange. For normal road use is this what you suggest?
I'd say it can be a life-saver to have the pressure just right, a digital pre-set electric pump is the best bet, that way, on a coldish/wettish day you can plug it up and go down to the level you feel is best. and on a hot day, go up to a level you prefer. Running low is ok at all times, but you will lose that kit-car sharp steering feel and burn rubber unevenly too... but the traction is mind boggling, and also you will notice that you get a good 2-4 times more time to correct on those back-to-front moments.... it takes longer for a tyre with low pressure to break traction, than it does on high pressure... and also note we do run low profile tyres, which makes them a liability on roads not suitable for a good blat... but do remember, drop the pressure too low and your wheels will take a pounding on potholes... so there is a compromise, I set mine all round to 22 psi for cold/wet days, and then up to 28psi for hot days... its a big step I know, but I am running 255/35/18's on front and 275/35/18's on rear, so a slightly different ball game to the standard cerbera sizes. Have a play, and you'll see what I mean.... you will notice a leap-year difference, its no wander they're so precise on the F1 cars about pressures cambers/toes etc... I dont think it would make a hell of a difference on a car that shoves over 3000lbs onto the fourwheels... but for our lightweights, its like night and day!
In the interests of perserving the tyres I've been running closer to 30 all round, it's luckly I like sliding about..... Gassing Station | Cerbera | Top of Page | What's New | My Stuff