Tyre pressure.

[Adrian Lazarescu]

Sorry if this is not the right place to post this but i need to know something about car setup. I downloaded the RD setup guide which i found very helpful(btw thx for the guide), but i have a question.
If you increase tyre pressure, does the tyre temperature increase or is it the other way around?

 

[Bram Hengeveld]

When you increase the tyrepressure the center of the tire will get warmer. Decreasing the pressure decreases the temp of the center of the tyre

 

[Adrian Lazarescu]

OK thanks for the reply. I was confused because i seen another forum where guys were arguing about it and i didn't know what to belive.

 

[Bram Hengeveld]

Thats at least what happends with my setups What i still need to find out properly what to do when track temperatures change dramatically and how to adjust the tires for that

 

[GAIAjohan]

Thats at least what happends with my setups What i still need to find out properly what to do when track temperatures change dramatically and how to adjust the tires for that

Well it seems logical that if track temps get higher, also the air temp gets higher. That means the pressure in the tyres get higher thus more wear on the center of the tyres.
If it gets colder the sides of the tyres get warmer because of lower air pressure due to less warmth.

 

[daRock]

Thats at least what happends with my setups What i still need to find out properly what to do when track temperatures change dramatically and how to adjust the tires for that

I've been testing that, and there are two issues.

The first is probably what you're wondering and I've been testing. So far it looks to me like about 4 clicks of air pressure is what it takes to deal with 10F change from your standard day temp. You reduce tyre pressure on a hot day and increase on a cold day, obviously.

The second question is one that is a bit annoying. Does it matter? It's annoying because as near as I've seen, if I don't notice the ambient temp, it doesn't seem to matter. So is this another thing Simbin has dropped? It appears so.

 

[daRock]

Oh yeah, there's actually a third issue.

Ambient temp or track temp?

It appears that ambient is a better marker as the track temp changes with time. Unless you check it right away, which is hard to remember, it's hard to guess what it was to begin with and what it'll reach during the race.

 

[Alen Pecanin]

decreasing tyre pressure will help your tires get faster warmer, but you will have a lower straight-out top speed. increasing tyre pressure will make your tires take longer time to increase tyre temp, but you will have a higher straight-out top speed than with low tyre pressure.

again that all will depend on the rest of your setup

 

[daRock]

The idea that higher pressure gives higher top speed is interesting. Do you have any figures and a way for others to prove that?

It does work in real life like that, but there are other effects. Like loss of traction when the tyre footprint is lifted at the edges and less rubber grips the road in the turns. And the gearing you worked so hard to perfect has now been changed.

The MoTeC program is a pretty good tool. It can be used to study how the tyre temps are affected. It would show how fast the tyres warm up for example. It would also be an accurate way to read the top speeds attained.

How much faster would you say the tires warm up from less pressure, and how much pressure change would you say would be needed.

Are you saying that having 100% of the tyre in contact with the road isn't as important as something else? what else would be?

 

[Attila Domján]

I used to pump up tyre pressure to max 190 for qualy, but i realized, that even in the first fast lap it is loosing already some traction compared to the outlap, and for qualy the best setup is also to work the middle temp right between the inner and outer, of course just at the end of 2-3-4 laps (i usually use 3, one outlap and 2 fast laps), so at the end it is a bit higher pressure then for race.

For temp change, i always take a look at track temp, and like darock said, around 3-4 clicks for 10 degree change is quite a good guideline.

 

[Alen Pecanin]

actually it is right, these are some basic tyre facts. no I dont have any figures or graphs, but why do u think they drive tour de france with small thin tyres and not with wide mountain bike tyres? because they would need more power to get to the same speed with the MTB as with the oridnary thin tyre.

but I said, the speed also depends on the rest of the setup, I dont just think about downforce but also ARB's, cambers etc. you can have a great WIN if you set it up the right way. if u dont, then you will see that others achieve bigger speed with the same tyre pressure it may be. so use your time to make a good setup, dont rush

dont forget, read my signature

 

[Kennett Ylitalo]

This is a great discussion and an interest of mine at the moment. After the last FDS lesson (thanks Bram, once again) i don't have a problem driving almost any kind of setup, not very fast but at decent consistency. I'm focusing on the tires now cause i destroy them too fast (that could be still caused by driving style). Temps seem to affect on the wear a lot which is obvious when you think about it. On some conditions tires work perfectly and setup/pressures affect as one would think. Too hot=too stiff has been a lot of times the answer. And usually what Alec said is usually true but then there are the these annoying exceptions. I would like to know what happens when everything seem to contradict the basics.

Some kind of testing is needed but that's hard when you're human.. Inconsistency, track layout etc. is the problem. Maybe on a oval that could be achieved? Driving constantly the same speed, same lines for a 10-20 laps and so on.. Maybe? Or some "driving robot" kind of player..

 

[Cristian Haba]

One of the reasons behind tire temps going up as you increase pressure is the rigidity of the tire as a whole goes up. A tire with higher pressure is more rigid thus when turning the car has the tendency to understeer when the pressures are set too high. (in general higher tire pressure front gives understeer and high pressure in the rear is oversteer for the same reason noted above)

Good luck with your sets, also Im wondering what type of car you're setting up FR MR or RR(aka Porsche lol).

 

[Kennett Ylitalo]

Tested exactly that tonight: lowered tire pressures and they didn't heat up to melting point so quickly. And the reason was just that i didn't need to steer so much. Only thing was that couldn't yet get the optimal center tire temp.

I tried with mini and the same old trusted setups. Didn't get much different track temps, all the time 27 so that part is still untested. Also it soo depends on the track you're on..

Oh, i drive FWD cars only at the moment.