njtls

how much psi should i put in a 225/45/18 SO3?

thanx

vclune

Air pressure is decided by how much weight is being carried and how fast you are carrying it. Start with the manufacturers spec on air pressure for the car. Should be in the manual or written on the door frame somewhere. Probably about 32lbs, for best traction and 35lbs for sustained highway speeds of 65 or above. If carrying four people on a long trip you could raise it to 40lbs, but you'll notice the grip start to taper off. You may get better mileage at the higher pressure. Do not exceed the max written on the sidewall and don't run the tire at this max number.

car_lost

for stock wheels, your are correct. but he is asking about 18's... therefore none of that applies.

im not 100% sure but i would say about 42 psi.

vclune

That was My opinion for the 18's. Tire pressure is still determined by the vehicle weight, not the tire size. This is just what I have understood when asking manufacturers this question. The specs are given for my 04 TL 18's and this is how it worked out. My opinion is that 42lbs is to much, but you can experiment with different pressures.

DOLEFEE

njtls, I've always heard 10 below the max psi OR 80% of the max psi. With my 235/35/19 Falken Azenis ST115, the max is 50 psi. I was running 40 all the way around but decided to bump it up to 42 for a stiffer sidewall.

Lawaia

Well said. This is why it's so important to select tires with the proper load rating.

vclune

FYI, my Acura 04TL 18's with 235/40 tires came with a spec of 39lbs front 36lbs rear cold. There is a new decal to install in your door frame with these specs when you purchase the Acura wheels.
The 17's with 235/45 tire spec at 32lbs front and rear.

JKJ

I will be receiving my O4 TL in about 2 weeks silver AT navi. i ordered the OEM underbody kit... thinking about the OEM optional 18" wheels... wanted some input. I know the ride will be rougher with the 18's but how much more rougher would it be. has anybody experienced both 17" & 18" acura OEM wheels. how smooth are they. here in NE the roads aren't as smooth.
just looking for some input.

As for tire pressure. Go with the numbers on your tire sidewall +/- 2psi. Too much beyond that, you're compromising your handling and traction.

vclune

The numbers on your sidewall are for max pressure only. There is never a situation where you would want to be even close to that pressure for everyday use. Max pressure on the stock 17's for example is 44lbs, but recommended pressure is 32lbs.

fsttyms1

most of it is up to the driver. the lower the # the softer the ride is going to be the higher the #(psi) the more firm the ride but better handeling. running 40-42 is a good #. its what i typically run on most of my tires (factory included)

njtls

thanx...i guess i'll run 40-42...cold right?

Cdn04TL

I have the A-Spec 18" wheels with 235-40ZR18 Michelin Pilot A/S tires....my dealer attached a label over the factory one stating 39 psi for the fronts and 36 psi for the rears.....my ride is firm but comfortable.

vclune

If you choose to run higher than recommended tire pressure you will decrease rolling resistance and improve gas mileage. You will also, due to reducing rolling resistance, reduce adhesion and handling will suffer. Tires will be more likely to lose traction easily, spin and or slide on corners. Tread will wear in the center of tire instead of evenly acrossed the pattern. Handling will suffer the most in the wet and feel very slippery. Tire pressure is determined by the weight it must support. Running +/- 2lb.s of max is not a good idea. This of course is only my opinion and you are free to have your own. A little time playing with the air pressure may teach you more than anything. Just trying to help you get the most out of your combination.