What tire pressure should I be putting into these size tires:

245/40/18

255/40/18


Normal driving and a road course.

Anyone share their experiences?

 

Tire pressure depends on the tire, wheel width, alignment and so on. Use recomended pressures for the street. On the track, start with 4 or 5 psi over recommended settings (maybe even up to 10 psi). Then, use chalk or white shoe polish on the edge of the tire to get the proper tire roll. You may have different settings front to rear. Lastly, you will have to change the balance for feel.

 

Yea, i was hoping for something i can start working with.

I just listed my tire sizes up top..

I m thinking 34-35 PIS for daily Driving?

 

That's sounds about right for cold pressure.

 

32 is what Mazda says, I think they know what they are talking about.

 

32psi cold will grow to ~38psi hot

36-38psi hot will grow to the low 40's hot (what I do) = better gas mileage

 

i dont konw.....i like running lower tire pressure at the rear when im on the track!

 

What are the trade offs though? Better gas mileage has to equal worse something.

 

Theoretically, if the tire is over inflated then you'll have uneven wear trending towards the middle of the tread.... But, with our negative camber, this isn't an issue - certainly not at 40 psi.

The only reason for running the rears a little below the fronts is to 'tune' away a small bit of oversteer. On the track, you can feel a difference.

On the street, I run 33psi front and rear, for no apparent reason. I can confirm (via my aftermarket tpms) a 4 to 5 psi gain cold to hot on the street.