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Alwysfresh
08-04-2004, 10:24 PM
I'm running 225/40 18's on my E36. Does anyone know what the correct tire pressure is for my setup?

BRAD 82
08-05-2004, 10:23 AM
generally speaking you should be running the bmw specs for tire pressure which i believe are located on the drivers door or in the manual. DO NOT use the psi indicated on the tire.

bimmerdreamer
08-05-2004, 01:38 PM
BUT, obviously he is not running stock tires so wouldnt the factories recommendations be obsolete. I would inflate to about 3-5psi under the maximum recommendation if its hot out, if it cold then a little less. Usuallly you want 38-42psi. Its much more dangerous to run an over inflated tire (blow out ect..) then an under-inflated one (bad tire wear)

Grimis
08-05-2004, 07:56 PM
i'm taking auto at centennial college and my alignment teacher said no matter what, you should go by the vehicle manufacturer's specs

BigD
08-05-2004, 08:28 PM
NOOOOOOOONONONONO, that spells a bent rim. Look at the range on the tire, and pump it up to the max, maybe 1 PSI less. Don't worry about overinflating, the max tire pressure rating is always stated to account for heat expansion as you drive.

Originally posted by BRAD 82
generally speaking you should be running the bmw specs for tire pressure which i believe are located on the drivers door or in the manual. DO NOT use the psi indicated on the tire.

thinair
08-07-2004, 12:04 PM
Originally posted by BigD
NOOOOOOOONONONONO, that spells a bent rim. Look at the range on the tire, and pump it up to the max, maybe 1 PSI less. Don't worry about overinflating, the max tire pressure rating is always stated to account for heat expansion as you drive.

I don't agree with that at all. The max pressure on my tires says like 51psi, which I would never run at, not even on the track and hot.

I'd recommend starting around 38psi, then going from there.

Also, blow-outs are pretty much non existant with radial tires, unless you're running WAY above the max pressure, or the max weight recommendations.

M3Turboca
08-07-2004, 07:18 PM
You should always use what is specified at the door by the manufacture or a few psi more if you prefer a firmer ride.

You should always adjust tire pressure when the tire are cold and not after you have driven them for a while.

Never as close as a few psi less than what is stated on the tire. You only need a high tire pressure for carrying excessive weight.

If the tire is sized properly for the cars weight then there is no need to go more than a few psi more than what is recommend.

Running too much will also cause the tire to wear out in the center. The tire will no longer be absorbing some of the road bumps making the ride too hard.

Justin e36
08-07-2004, 09:22 PM
ok.. so what's the factory specs for e36 tire pressure?.. does it change depending on if it's a 318... 325/328 or m3?

Mystikal
08-07-2004, 09:34 PM
Originally posted by BigD
NOOOOOOOONONONONO, that spells a bent rim. Look at the range on the tire, and pump it up to the max, maybe 1 PSI less. Don't worry about overinflating, the max tire pressure rating is always stated to account for heat expansion as you drive.

That is some terrible advice man. I hope you're not doing that to your powerful car. You'd have an effective 50mm contact patch.

To throw in very general advice, run mid-high 30's and adjust as you like to compensate for understeer, ride quality, etc. Unless you're an old geezer you wouldn't want to go below 35PSI.

///M3
08-08-2004, 05:18 AM
when i used to work at tire depot we would set all cars to 34 psi
some performace cars would get 36-38 tho

BigD
08-08-2004, 03:03 PM
Originally posted by Mystikal
That is some terrible advice man. I hope you're not doing that to your powerful car. You'd have an effective 50mm contact patch.

To throw in very general advice, run mid-high 30's and adjust as you like to compensate for understeer, ride quality, etc. Unless you're an old geezer you wouldn't want to go below 35PSI.

I don't think so. The fine tuning of pressure is up to you but certainly NOT what is on the door IF you are running low profiles. You have stock rims, that's fine. He has an E36 with 40 profile tires. If he runs the stock pressure or even close to it, he will bend his rims, I guarantee it. It really isn't a coincidence that the OEM pressure reccomendation for 60 and 40 series tires varies by 10PSI?

The 17s on my car are stock so I do run stock pressure. But when I had the 535, which came with 15s stock, and I was running 18s, you can bet your ass I was running the tire spec. The stock was like 28, I was running 40. And my contact patch and wear was just fine. Once you change the rims so drammatically (+3 diameter and +2 width) the stock pressure sticker can be thrown away.

Read point 3:
http://www.toyo.com.au/TechInfoPDFs/TTT-123%20Inflation%20Pressure%20Part3.pdf

Mystikal
08-08-2004, 11:23 PM
What you just said made quite a bit of sense. I understood what you meant earlier, but what you suggested about inflating to max specs is insane. As Nelson pointed out, a very popular maximum is 51PSI, and a tire driving around with 50PSI as you suggested is just crazy.

Also in that link they go from a 195/65/15 to a 215/45/17, and they increase it from 28 or 34PSI, or around 21%. So for an E36, going from a stock 205/60/15 to a 225/40/18, let's use the same scale and add 30% to the stock 15" requirement. Even if it is 32PSI, that's only 41PSI. I know this is a very rudimentary approach, but you see what I'm saying. 50PSI is nuts.

thinair
08-08-2004, 11:53 PM
Well, if I look on my door jamn for example, it says right there, for a 235/40/17 wheel, which is a stock tire size (on the M3) to run 36psi front, and 33psi rear.

I follow that and haven't had problems, when I'm at the track I run 38f/36r with no problems

Oddly enough, the tire pressure for a stock 195/60/15 32psi front and 35psi rear.

BigD
08-09-2004, 12:05 AM
Oh, well yeah. Everything needs to be taken with some common sense. Besides, I only gave a starting point. Tire pressure opinions are like assholes, every instructor at the track has one and they're all quite different. Personally I'd start a 50max, 40 profile tire at about 45 and experiment, but wouldn't go below 40 for the rim's sake. But yeah, point is, being absolutist in any situation (high or low) is stupid.

On an unrelated note...I just caught Street Fighter on Space... is that fuken Kylie Minogue? Damn she fine