SlifoxS

what's the best psi to have these tires at?

(The stock Pirelli's)

Infernokron

I believe recommended preassure is 30 PSI. For tire longevity, that's probably the best. For performance, you can try stepping it up some, say 35 PSI or so. I believe that's what my bro runs in his SS/SC for normal driving, then 40 PSI for Auto-x. You have to understand though that increasing the preassure will most likely wear the tires out prematurely.

InfinityzeN

Normally, the best thing to go buy is max-10. Meaning the max tire pressure listed on the tire -10%. There is a whole section on it at the Suspension Bible. And Infernokron, it the tires are rated for over 40psi and your running them at 30, they will wear out faster then normal. I think part of the problem with people wearing out the stock tires is running them at too low a psi.

an0malous

look on the inside of your drivers side door on the frame below where it latches.
32psi is the recommended pressure

InfinityzeN

And what is the recommended pressure by the tire manufacturer? Max pressure should be on the tire.

BlackBaltSSNA

so if the car says 32 psi but i got aftermarket wheels kumho ecsta to be exact on the tire it says max pressure is 50 psi...i should be putting 50 psi on my tires?

jasz71

Never run what the side wall says. You will have a harsh ride and premature wear. Hit a pot hole and could puncture it. 32psi is recomended.

Thanks J

an0malous

50psi lmao.

dear god....thats what the tire is telling you is the absolute peak before it will risk exploding in your face!

just put 32psi in.

Infernokron

I've never heard of that before, thanks for sharing InfinityzeN. I'll have to look into this more, from what I can think of off the top of my head this would seem to make sense. +rep for usefull info.

THANK YOU an0malous!!!! I'v been trying to think of a good way of explaining this to members at work. It's so aggravating when people say "Well I've been running the tires at the 44 PSI recommended on the side of the tires...." .



P.S. I can't believe I got the recommended PSI wrong in my first post .

BlackBaltSSNA

yea misunderstood his post thinking he meant that what the tire wall says is the max pressure that that is the max pressure that should be on the tire see where my confusion came in? and also on his post it says max pressure -10 then -10% way different from each other if we went by -10 than my psi would be 40psi if by -10% than it would be 45psi

madeinUSA

I know from my experience the car handles& feels much better with 36-38 psi cold which is several more PSI than stock..

InfinityzeN

The rule is called max-10. It means take the max and subtract 10% as a rough starting number. It will handle and give better road feel, plus slightly improved gas mileage. If it is too stiff a ride for you, drop the psi down a couple to about -20%. For a 40psi max cold tire, such as was the most widely used in the 90's, that would put you at 32psi cold. Tires today are rated at higher psi, but car manufacturers never changed their recommendations.

tio

Max tire pressure-should NEVER be used on a passenger car. The max tire pressure is to be used when using the tire to carry its' maximum load carrying capacity. I think the stock tires have around 1400lbs each. Unless your car picked up an extra ton, bad idea.

A tires main function is not traction, it is to hold the air that carries the weight of the vehicle above it. Tires are generally made by tire manufacures to be sold for more than one type of car. That is why the automobile manufacturer will list a specific tire pressure spec for each vehicle, based on vehicle weight and weight distribution.

You may identify if tire pressure wore out a tire by looking at the tread. If the outside shoulders of the tread are worn more, then the pressure was too low. If the inside portion of the tread is worn more or has a up/down uneven wear then it had too much pressure.
It is all about contact surface with the road.

You will get slightly better gas mileage by over inflating a tire because, less tire tread makes contact with the road giving you less rolling resistance. The cost of the premature tire wear will not offset the gasoline cost.

Tire pressure may be managed for specific application, by those who truly understand the nature of the tire and vehicle, and are willing to adjust tire pressure on a daily basis. If you want to just leave them at a set number go with the OE suggestion.

Steve.

Noob

I heard to get the best traction you should underinflate the tire. How true is that?

Left

True as far as I know. You can't run it flat, but lower air pressure will give you better traction, but you're going to wear the tires out faster and get less MPG as well.

InfinityzeN

They will handle worse in hard cornering underinflated.

an0malous

yeah its more of a straight line thing.
just to give the biggest contact patch, and to allow a little sidewall deflection to stop the tire breaking loose as much.

Ive seen definate results dropping to 24-26psi.

but im sure to go back to 32psi right after my track days.

NS06G5

yeah "airing down" is mostly used by off roaders when they need maxium traction, like for rock crawling, but I wouldn't recommend if you were going to travel over 10 kph, as it will tear the guts out of your sidewalls and probably break the bead.

2.4SlowassBalt

i keep mine anywhere between 31 and 33. but for a 2.4 if im not mistaken it says 35 on the door.