Time attack tyre pressures
 

Hi all,

I plan on doing some time attack challenges in the summer and was wondering about what tyre pressures to use.

The guy that previously had the car used it for this same exact thing and even won the class. Sold me the car with his old Nankang AR-1s on ProTrack wheels (lightweight track rims) so it would be a shame not to use them.

Bought some Michelin PSC2's online as they were at a discount so i will be using these for my time attack challenges (the AR-1s are almost completely worn out, might just use them for a light track day then dump them).

Anyone of you guys ran Cup 2's before? What tyre pressures did you use?

:popcorn:

20 F
35 R
:party0030:

You're going to want to use a pyrometer to dial in the tire pressures.



https://www.turnology.com/tech-stori...-to-go-faster/

This is the only way

It will also show up issues with alignment settings

Take your time

Take notes

Michelin says 33 to 40 psi hot:
https://marketing.michelin.co.uk/p/P...etin_PSC2R.pdf

Most radials will have a very broad range of pressures over which they will work fine. Some think "lower is better" but I disagree... I usually run 34-36psi hot. Unless you have a lot of tires and dedicated test time at the track, you're not likely to ever know if you are optimized, even with a pyrometer. If you *do* use a pyrometer, be aware that "even temperature across the tread" is NOT the ideal. optimized setups will usually run a bit hotter on the inner portion of tread.

Just run 34-36psi hot and don't worry about it, until such time as you can have a dedicated test day at the track to record data with dozens of tires, and several techs to help out with measuring tire temps and pressures and to analyze lap times and data.

In addition that for max grip one needs to dial specific hot pressures, so not sure if manufacturer data really should be much relied on, i somewhat doubt that overheated from track use temps are really "hot temps" provided by manufacturer data, which i rather expect from normal driving on public roads,
there is also bit, that different sized wheels/tires also may change what pressure is needed. For example when install wider tires holding more air volume, less pressure needed.
Pirometer is more then worthy purchase for most tracking their car and to whom matters maximizing grip & be more competitive & faster. Cheapest ones are not that expensive, and given that many spend on way more expensive other mods on car, more then pays off. (worth noting that it's better to buy needle stick in tire type pyrometers, not "IR gun" types, as when one drives in pits, tire outside already cooled off, while temps deeper in rubber drop off slower, thus are more useful for data). Dialing pressures (and alignment) with pyrometer also can help with providing individualized data for specific car/driver's driving style/weather/track, letting it really be THE right settings instead of some ballpark initial numbers, and also letting to dial sooner then deciding on change after eg. uneven wear had already happened.

Clearly you did not read the link! The Michelin Pilot Sport Cup 2 is marketed as a track tire, and the pressures recommended are for track usage.

Whilst on track, hot pressures should be between 2.3 bar and 2.7bar (33psi to 40psi). 2.5 bar (36psi)
gives optimum performance.



Without going into a point-by-point on taking tire temps with a pyrometer, in my experience at the track with hundreds (thousands?) of students and fellow competitors over the years, my impression is that the VAST majority of them are better off just running 34-36psi hot and not worrying with pyrometer data...

this. I’m assuming lighter cars will be on the lower end of the scale.

In my experience (limited) this seems to work well. The pyrometer I’ve found is more for checking alignment as unless you can check overall temps the second you pull off the track on a hot lap the data won’t be accurate I’m assuming

Well you've used the link for the Cup 2 R's which are softer than the normal Cup 2's. Doesn't Toyota recommend 35 psi on the stock 17 inch wheels? I guess i'll just be starting out with 34 hot and go from there...

I was hoping someone here had some experience with these particular tyres so I'd know how they handle in hot weather (it gets close to 100 F here in Bucharest) and adjust pressure accordingly

Tire pressure doesn't have anything to do with the wheel, don't worry about what the sticker in the door says. You are not going to get much input on here about Cup 2's as they are not popular, they are just too expensive.

34-36psi hot, you'll be fine...

No one is going to be able to tell you what is "optimal" for your car on your track(s). Without further research on Cup 2 (non-R) vs. R, I'm sticking with 34-36 hot as a good place to be...

Again, there is going to be a quite broad range of pressures that will work fine without making a huge impact on lap times. The absolute sensitivity of lap times to hot pressures is going to be quite low as long as you're within that broad range. Being a little on the high side is generally going to be safer, give reduced rolling resistance on the straights, will produce less heat, give longer tire life, and feel better in transitions vs. being on the low side.

34-36 hot, you'll be fine...

Listen to @ZDan on this one and dont over complicate things. You'll know what to do once you get to know your car and the tires you are using.

I used to run 38(my gauge) hot with Nitto nt01`s. That temp suited two drivers and would be anywhere from 28-32 cold, conditions depending