Optimal Tyre Pressures - a guide

mrx · Post by **mrx** » Sat May 14, 2005 7:02 pm

I am interested to know what pressures people set when going on the track.

*looks at Steve and Rob*

Just as a general guide - obviously every car is different, and everyone prefers a slightly different balance etc.

Just looking to save myself some time and effort! I am looking at probably around 38-40 on the fronts, and 32-34 on the rears?

RichardH · Post by **RichardH** » Sun May 15, 2005 1:35 am

For road tyres, on a tight course, I use around 40psi in the fronts, and 35psi in the rears.

If you use much less, you'll wear the outside edges on the front tyres during a sharp turn-in, as the tyre edge basically rolls underneath.

But on a longer, faster course, you could find yourself wearing the front tyres' centres (or even the insides if you have extra camber) as you brake in a straight line.

It's all a bit of a juggling act! Remember also that your pressures will increase as your tyres get hot. If you plan on doing a decent session, start a little lower, and give them time to heat up.

- Rich

Post by **smorison** » Mon May 16, 2005 9:43 pm

for normal road tyres 40psi (HOT) is right... it can be a bit hard to get there with variable temperatures ...

rears are a bit hard... i'm yet to get a honest answer from anyone who actually races fwd cars as to what to put them at... i haven't had a decent set of race tyres on for a while so i haven't had much performance difference with pressure changes...

on the camber ... anything i've had over -1.5 just burns up the insides of the tyres either through lockups or no traction out of corners... the rears well depends on how much body roll you have...

RichardH · Post by **RichardH** » Tue May 17, 2005 2:01 pm

smorison wrote: rears are a bit hard... i'm yet to get a honest answer from anyone who actually races fwd cars as to what to put them at... i haven't had a decent set of race tyres on for a while so i haven't had much performance difference with pressure changes...

Yes, there's a bit of an art to rear tyre pressure!

I've used r-spec semi-competition tyres for a couple of years now. Last year, I was running the fronts at a steady 36psi and playing with the rear tyre pressures.

At 28psi, there was noticably more movement from the rear of the car on sharp turn-in. It was quite loose, and was pretty quick as a result - the car "wanted" to rotate.

At 30psi, there was more grip at the rear. As a result, it wasn't as loose. Driven exactly the same way, it wasn't as quick.

However, coming into the corner a little faster, and trail-braking a little more got more weight off the rear tyres, rotated the car just beautifully. This was quicker with the rears at 30psi than at 28.

So just 2psi changed the way the car handled, and warranted a different driving approach. Less grip at the rear meant it was more prone to rotating, but you couldn't overcook it. If you did, at high speed, it resulted in big rear step-out, opposite lock, etc. Good to watch, but can stuff up your whole session!

Hope this helps!!

- Rich

mrx · Post by **mrx** » Tue May 17, 2005 7:30 pm

I actually went with around 38 on the fronts, and 32 on the rears, and so long as you used a bit of trail braking, and kept the speeds up, the back really did want to come around nicely.