[Marto]

Gentlemen,

Regarding the black science of tyre pressures for track days, I was always told the rule of thumb was the std pressure on the plate inside the drivers door + 5psi.

Is this a good yardstick, or is there a more specific range.

For the 1st time in 4 yrs of M5 ownership, the old girl will get to play on some tracks this year!!

Cheers

Marto

 

[mattmartindrift]

All depends on the tire. The door's pressure is based on the weight of the car, and a few tire characteristics.


What tires are you running?

 

[E55AMG2]

Gentlemen,

Regarding the black science of tyre pressures for track days, I was always told the rule of thumb was the std pressure on the plate inside the drivers door + 5psi.

Is this a good yardstick, or is there a more specific range.

For the 1st time in 4 yrs of M5 ownership, the old girl will get to play on some tracks this year!!

Cheers

Marto

The proper way to do it is to start at your street pressure, and air up/down accordingly by checking how far the wear goes towards the edge of the tire. There are little triangles (or something of the like) to show where the tread ends. You want the wear to hit the tip of the triangle and no further. That's how you should set tire pressures.

 

[gsfent]

The proper way to do it is to start at your street pressure, and air up/down accordingly by checking how far the wear goes towards the edge of the tire. There are little triangles (or something of the like) to show where the tread ends. You want the wear to hit the tip of the triangle and no further. That's how you should set tire pressures.

Using white shoe polish works well. Just mark 3 or 4 places around the tire, across the outside of the tread and down the sidewall a little and then you can see how much the tire has rolled over by where the shoe polish is worn away. This assumes you are driving relatively hard to get an accurate reading.

On a heavy car like ours, I don't want to see more than 42-43 psi hot on the outside front tire. Depending on starting temperature, expect about 5-6 on the low end and 8-10 psi growth on the high end from your starting street pressures. Having a tire pyrometer would also help.

Regards,
Jerry