Tyre pressures

DC · 09-03-03, 06:07 PM

I just had a puncture mended on a front tyre (screw in the tread from Knebworth). The guy put in 32lbs of pressure but it set me thinking about the pressures I am running.

I have 235*45 on the front and 335*35 on the rear, anybody recommend some settings - I was runniing 24 front, 22 rear, which seem too low to me.

Thanks

Malcolm · 09-04-03, 06:50 AM

I think to get any sensible info back on this you will need to state what make of tyre, which rim size and what you intend to use the car for. All these fatcors will affect tyre pressures.

Malcolm

DC · 09-04-03, 04:44 PM

Malcolm,

They are Pirelli P Zeros, 17" rims. I just wanted a sensible pressure for road use.

roy snook · 09-04-03, 04:55 PM

David,
I run the same size tyres as you and I run 23PSI at the front and 25PSI at the back but I can see less wear in the centre of the rears and slightly more towards both edges

DC · 09-04-03, 05:00 PM

Roy,

I got it the wrong way around. I run 22 front and 24 rear. I have wear on the outside of the tyre at the front but I think this was due to incorrect tracking. I am going to try increasing the pressures a little 24F/26R.

Martin Weigold · 09-04-03, 07:18 PM

Dave,

I have exactly the same tyres as you. I find that front 26 and rear 28 psi is a good combo for sprints such as Goodwood or Lydden, but on the road I take the pressures up to 29 front and 31 rear.

Personally I think the pressures that you are running are too low. Dave Parker and Paul Thompson are very knowledgeable in this area if you want further advice.

DC · 09-05-03, 02:27 PM

Thanks for your information, Martin.

I have tried 26 front and rear today. It is happier on the motorway. I may try a few more pounds in the rear. Looking at the profile with 22 psi in the front made them look slightly flat.

Malcolm · 09-05-03, 03:50 PM

Definately running low tyre pressures if you have wear only on the edges. Too high tyre pressure will wear the center out first too. Equal wear equals right tyre pressure. If you have a tyre temperature meter you can use temperature readings to give you quicker analysis. Hot sides and cool centre = low. Hot center and low side temps = high. If you have one side higher than the other then you are looking at camber angle changes. Or if it is just left hand side on left hand tyres, try going slower round roundabouts!

Malcolm

roy snook · 09-05-03, 04:50 PM

Hi Malcolm,
I'll be running higher pressure in rears to even out wear pattern, although Martins 28 PSI seems rather high. I wonder what formula tyre manufacturers use to determine recommended pressures-vehicle weight x tyre width x dia? [img]/ubbthreads/images/graemlins/confused.gif[/img]

Malcolm · 09-08-03, 05:59 AM

Roy, If you run high pressures just to even out wear expect your handling to change, maybe for the worse. In competition on a copletely different tyre to what you use, I have found 2lbs pressure changes makes for different handling characteristics. CF the cost of an off to a tyre temp guage and perhaps consider biting the bullet on the cost of having worn the edges of the tyres instead of even wear.

Malcolm