tyre pressure for track day?

[1590cc]

I've been running 24-25psi... gets to around 30psi when hot on R888 and V70A

[89lude]

that would be because you have a semi slick with a stiffer side wall? is that on a 16 inch rim/tyre just for future reference as i would like to upgrade to some r888 in future

[AE092]

I just did a track day with a few guys (novice/new to it all) and I recommended 32psi front and 34psi rears - cold. Friend was on Toyo Proxes T1R so not too far off your Falken RT615's (more comparable with R1R's) but regardless, once he lowered it down to them and got used to it, he managed to go 3 seconds quicker (after I showed him the lines he could work with). Here's a tip, don't go lowering your tyre pressure all the way down at the beginning of the day, start of gradually until you find the psi that suits your driving style. Some guys like it higher/lower than others. If you lower it too much on the day and do not have the opportunity to reinflate at the track then you'll have to make do.

I was on semi 15' RE55S semi slicks: 26.5psi all 'round, after having 28psi caused my rear end to be too tail happy and lose it into the gravel.

[integragsi96]

what would someone suggest i run on kumho ku36's 225/50/16?

[AE092]

When I had KU36's, I kept it at 29/30psi cold. They are dependent on the temperature of the day, the hotter the day the faster/more they'll heat up. I had the 205/50/R15 size, tire pressure recommended is for track. For street, they stayed at 33/34 psi all 'round.

[rpm boy]

what are the rim to tire width percantages you guys are using also? there isnt alot of information out there in relation to corner weighting, tyre footprint ans rim/tyre width percentage. would be good to get some decent info and also setups with track times

[gbpracing]

With street tyres, you want to keep the pressure high like that because the sidewalls aren't as strong as say a semi slick. Ive seen people run with 40, and have shredded their tyres. I guess it all comes down to what brand/model tyres you use. Also, that american pro driver guy that goes to the circuit club track days told me to run it at 45, so i did

SpoonS has it right, street tires are needed to be higher pressure for the track due to the weaker flexable sidewalls. The tires can get chopped out due to tread blocks moving around under load. Eventually tearing away.
If your going to do track days get a spare set of wheels and semi slicks and enjoy the lap times tumble. Save your good street tires for the street.

[Stevil]

89lude I run Fed RSR 205/50/16 at the track (Done probably close to 500 laps at 7 track days) and they are a simlar tread wear to your RT615. Now I've played with everything from as high as 45 down 32 and I've come up with 38psi for the front 36psi for the rear. The RSR do have a stiff side wall but seeing as your 45 profile is a little less I'd expect you best pressure wont be far off this.

Randy 40psi is gunna be too high for the RSR I reckon, I set my best times when track temp got to 29C back in Feb, was running 38F/36R. keep in mind my FD1 is fairly front heavy with 60/40 weight bias.

[munkaii]

There's a few factors that need to be considered when deciding on tyre sizing and tyre pressures.

As some people have mentioned, street tyres have less stiffer sidewalls than semi-slick tyres and hence you NEED to run them at a higher pressure. There are two main effects associated with this:

1. Higher tyre pressure --> higher sidewall stiffness --> the tyre is able to retain shape as opposed to rolling over excessively and potentially separating from the rim.

2. Higher tyre pressure --> smaller contact patch area --> less grip but better TYRE WEAR. A lot of people still run low tyre pressures because they want to gain that additional grip, however you run a much higher risk of the tyre falling off the rim and you will shred tyres significantly quicker.

If you wanted to think into it further, lower tyre pressures would mean better lateral corner grip in the sense that the contact patch is greater at a sacrifice to the rolling behaviour of the car. A car with lower tyre pressures will roll more, which actually reduces cornering grip. So it's a compromise between the two. Higher tyre pressure is always safer for a street tyre.

[89lude]

Thanks for info guys but this thread was bumped by a question above which should be answered instead of mine. This thread was from almost a 18months ago

[r3ckless]

Point beiing? Its always good to have these informative threads for new pnes comming in and wanting to know about tyre pressures.

[rpm boy]

How is everyone actually testing there tyre pressure and contact patches for best grip? is everyone just dong trial and error and associating there pressures with lap times or are you setting the pressures, checking the contact patch and then trialing it on the track?
i think everyone on here has the right idea but does anyone have an example of how they actually check there contact patch/ tread pressure contact on the road....