A basic guide to tyre pressures

[Multics]

I found this on another forum I though I'd post it on here.

 

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I've been looking for the correct pressure to run my new tyres at, and found rather a lot of not much. So I went hunting, and didn't find a lot more, until I stumbled across this, which is what I am using. Thought you folks might like to use it as well.

 

The baseline method from Oscar Pereda of BF Goodrich. He suggests this as a good starting point if you have abolutely no guide as to what pressure to use in your tyres. This starting point should be regarded for road use only.

 

(Vehicle Weight in pounds imperial/100) + 2 psi at heavier end + 2 psi all around if suspension and alignment are stock.

 

Example:

 

Stock 911, 3,000 lb.

(3000/100) = 30 psi

Add 2 psi all around = 32 psi

Add 2 psi to heavy end = 34 psi at rear

 

With modified suspension, the result would be 30 psi front, 32 psi rear.

 

SO:

 

Stock Supra mkIV TT = 1581kg = 3486lb.

 

3486/100 = 34.86

 

Non standard suspension, so only adding 2psi to heavy end.

 

36 psi front, 34 psi rear.

[AlanM]

I have tried a few different pressures over the years, still end up back at 36/36

[Al Massey]

I have tried a few different pressures over the years, still end up back at 36/36

 

Im at 36/36 too

[bigbloodyturbo]

36 front and 34 rear is what I run on mine after reading a few threads on here recently.

[MarkR]

I find it also depends on the make of the tyre. My Michelins need less air than the Eagle F1's

[tbourner]

So I should be putting 48psi into the Delica!!

[Lbm]

36psi F & R for me since 2001.

[Bryan_Jones]

I've been running it at 32 for a while and I noticed increase tire wear on the edges. Started topping it up to 34/35, but I'm going to try running it at 36 all round.

[madwoody1]

I normally run mine on 37 psi but then again thats from tesco and is there gauge calibrated?

[1JZGTE]

Maybe I am wrong, but I thought it would be better to run lower pressure on fronts and higher on rears as the Supra is RWD...although I can't remember the reasons for this, just remember reading about it on the interwebz, somewhere

[Terminator]

Oops

Edited April 26, 2009 by Terminator (see edit history)

[Terminator]

As the article says, this is just a starting point. You need to monitor tyres closely to see if wear is even. A good quality digital infra red temperature gun will help get pressures spot on by identifying hotter or cooler areas of tread.

 

I use my own calibrated compressed air inflater/gauge for all our cars. I have been using 34 front and 33 rear on the MKIV for the past 8 years and get even tread wear across all tyres on both 17" and 18" rims and a variety of tyre compounds. I never use forecourt air systems any more as I have found them to be up to 5-8 psi out.

[wile e coyote]

Interesting

[Ian C]

I have been using 34 front and 33 rear on the MKIV for the past 8 years and get even tread wear across all tyres on both 17" and 18" rims and a variety of tyre compounds.

 

I've always used Pirreli P0s and I have to run 28psi at the rear to even the wear out, otherwise the middle of the tyre wears faster than both edges. Whats that all about then?

 

-Ian

[AJI]

As tyre pressure 1stly starts with car weight as the main factor it is always best to use stock pressures as quoted from the manufacturer.... whom will have spent the required amount of money on research and testing to arrive at that stated pressure.

 

If you are on modified suspension, wheels, alignments etc. etc. .... then there can be no other way but to trial and error yourself.

 

By this I mean start at the stock pressures and then record tyre wear for the outside/middle/inside of each tyre over a certain amount of miles.

Then adjust the pressures as required.

 

 

If for example any tyre is wearing out in the middle faster than the inside, then reduce pressure by 2psi.

If its the other way round then increase by 2psi.

 

Each car will be slightly different due to wear and tear on bushes, alignments, weights, driving style, tyre type, etc. etc. ... so the only way to get the 'perfect' pressures is to trial and error yourself.

[SimonT]

I was told that you use stock pressure then add 2psi for every inch you go up in wheel size?!!

 

Say for example Stock 17's you have 34 psi and then you buy 18's you then put 36 psi in??

I may be completely wrong?

 

What do Toyota say the stock pressure should be?