Rear tyre pressure goes up - why?

[n00b]

Background: I've got some 205/55/16 Toyo R1R semi-slicks on some el cheapo rims. I've got some -2 to -3 deg of neg camber up the back end, running stock SS+ shocks, lowered springs and front/rear beef'ed up sway bars.

Problem: front and rear both set at 33psi, the front remains the same YET the rear rises up to 37-38psi even. I know when tyres are set at the correct tyre pressure there shouldn't be enough heat generated to cause the rise but if I do set it to 37psi, the rear tyres are still going up to 41psi even after a short drive.

On the other hand, I've also tried dropping it down to 27psi for the rear but it doesn't take too long before they come back to 35psi. What's happening?

Thanks in advance

[timmydamini]

Hi,

Tyre pressures normally rise with heat resulting from use.

Just for a comparison.

I use Kumho V70a 205X45-16 on track. I set the cold pressures to 41psi front and 30psi rear. These rise to 50 and 40psi respectively.

At this this pressure I find the stock MCS handling to be quite neutral, (once the tyres heat up). I used to run less pressure in front but was getting too much understeer.

Tyre pressures are a personal prefference. It's the only way of tuning the handling of a stock MCS.

Hope this helps.

Tim

[mightydread]

Quote: Originally Posted by timmydamini

Hi,

Ture pressures normally rise with heat resulting from use.

Just for a comparison.

I use Kumho V70a 205X45-16 on track. I set the cold pressures to 41psi front and 30psi rear. These rise to 50 and 40psi respectively.

At this this pressure I find the stock MCS handling to be quite neutral, (once the tyres heat up). I used to run less pressure in front but was getting too much understeer.

Tyre pressures are a personal prefference. It's the only way of tuning the handling of a stock MCS.

Hope this helps.

Tim

wow thanx for the info
mightydread

[Sands]

The rule of thumb is 1 psi for every 10*F. So going up ~4-5 psi is reasonable.