Max Tire Pressure?

[dvdt]

The max tire pressure listed on the tire, is that when the tire is cold or when it warms up after driving?

 

I have T1-Rs and the max on the sidewall says 44 psi. They where at 37/36. The corners are wearing more and the inner tread is holding up surprizingly well after 15k. So I'm raising the pressure to 40/39psi cold. Will this be ok?

[xr7kid]

max listed it cold psi.

[meier motor sports]

my eagle f1's do the same

[Xenonk]

it's on the side of the tirewall (noted as a cold temp)

[Scooter]

Should be fine. Yeah, in general you want to stick with the tire pressures recommended by the car, but that 44psi is the max rated pressure the tire is good for so you should be fine going to 40/39 based on your own driving style / tire wear. I believe that 44psi rating is the cold temp as well - I've never seen anything but cold temps spec'd for tires. I've got T1-R's on the Miata, myself, and I do run a couple extra PSI in them, too. You're golden.

 

Wow, three people pimped me while I was typing, but at least it seems to be a consensus!

[sframs]

on the potenzas it's suppose to be 32/30. do you go higher than that?

[VTGT]

My mpg has been pretty bad lately how much can tire pressure affect this. I think im a little low i will check tommorow? 35 all around so good?

[rkl303]

I think it also depends on how you like your handling. I think xenonk posted saying lower pressure in the rear will give your more over steer and vice versa for the front.

 

I am running 33 31 on the RE92's(I can't wait to get off of them) and mpg is not bad at all (25-26) except that my driving is all highway. My friend commented that my handling is neutral or maybe a slight amount of oversteer.

[Xenonk]

^ actually, that really depends on a lot of issues.. if the tire is rolling over, you are basically understeering. If you pump up the tires too much, you will end up lessening the contact patch, which could go both ways to handling when it comes to tire pressures, but since the rear end is light, increasing pressures in the rear will make the car oversteer.

 

When it rains, I drop some tire pressure to get some grip. Basically I am softening the tires up to soak up the hydroplaning situation.

 

But yes, tire pressures do affect fuel consumption. You can see as much as 75 miles out of the tank. I drove from MD to FL on 38 psi on the way down, got around 400 miles to the tank.. on my way home, I forgot to fill the tires back up (it was raining and wet during the autox event), so I drove home on 25~27 psi range and I lost about 75 miles out of the tank.. I was puzzled how the car was lower on the miles, then on my gas stop, I pumped the tires back higher and I got back to the 380 to 400 mile range between fill-ups.

[Vimy101]

The max tire pressure listed on the tire, is that when the tire is cold or when it warms up after driving?

 

I have T1-Rs and the max on the sidewall says 44 psi. They where at 37/36. The corners are wearing more and the inner tread is holding up surprizingly well after 15k. So I'm raising the pressure to 40/39psi cold. Will this be ok?

 

Tires are designed and tested to run at the max cold inflation pressure. OEMs have their recommended inflation pressures to acheive their own idea of handling charateristics. Remember what happened to the Ford Explorer where they recommended an under inflated condition to lower the vehicle's center of gravity which resulted in catastrophic tire failure.

[ilh]

Keefe,

 

I would expect hydroplaning to be worse with lower pressures. Tire Rack data seem to support this with worse contact going from 35psi to 30psi, and even worse down to 25psi.

 

Why do you expect it to be better with lower pressures?

 

--Lee

[Xenonk]

Keefe,

 

I would expect hydroplaning to be worse with lower pressures. Tire Rack data seem to support this with worse contact going from 35psi to 30psi, and even worse down to 25psi.

 

Why do you expect it to be better with lower pressures?

 

--Lee

 

 

nope, I learned from national autox drivers

 

the logic is that if you have too hard of a surface, you are going to skimp right over the water.. think of it as a wake board or a water ski where the surface is hard...

 

when you soften the suspension, this allows the suspension to soak up the energy, this also gives time for the tire cut into the water since it's not as stiff (so think what will happen if you had a sponge for wake board or a water ski).

 

Also, an alignment such as having toe-out up front will promote understeer on our cars in the wet (did about an hour worth of wet skid pad excersises when I had the WRX for drifting school at Summit Point Raceway).

 

Remember, the wet enhances driver mistakes, so if you have an already stiff car in the dry and it's already slidding around, just imagine when you are in the wet. Softening the suspension and tires will give you some room for error in driving input.

[Garandman]

There are a few ways to get it right. One is to ask in a forum like this.

 

Another is to get a tire pyrometer, drive the car hard for a while, then measure the difference in temp across the tread. You can usually see if the tire is rolling up on the sidewall in hard cornering, not to mention understeering.

 

Is it wearing on both outside and inside edges, or just outside? Have you rotated them lately? Both sides wearing the same? Feel good about alignment?

[VTGT]

^ actually, that really depends on a lot of issues.. if the tire is rolling over, you are basically understeering. If you pump up the tires too much, you will end up lessening the contact patch, which could go both ways to handling when it comes to tire pressures, but since the rear end is light, increasing pressures in the rear will make the car oversteer.

 

When it rains, I drop some tire pressure to get some grip. Basically I am softening the tires up to soak up the hydroplaning situation.

 

But yes, tire pressures do affect fuel consumption. You can see as much as 75 miles out of the tank. I drove from MD to FL on 38 psi on the way down, got around 400 miles to the tank.. on my way home, I forgot to fill the tires back up (it was raining and wet during the autox event), so I drove home on 25~27 psi range and I lost about 75 miles out of the tank.. I was puzzled how the car was lower on the miles, then on my gas stop, I pumped the tires back higher and I got back to the 380 to 400 mile range between fill-ups.

 

 

so for better fuel economy it would be safe to run 38 all around on re92's?

[Xenonk]

^40 front and 36 rear cold is fine since the tires are so upright (no camber),

[wukindada]

I run 39f/37r cold on my T1R's.....even after 14k there is over half of the tread left:)

[Vimy101]

40/40 here.