Quote:
Originally Posted by ChrisBuer
I'm interested in this thread as my next mod will be a full set of PSS tyres, once my PS2's are worn out.
However, the pressures being mentioned (34psi rear and 36psi front), are these higher than the stock pressure ratings? I can't remember off the top of my head but as I am also running more power and torque I wonder if I should be increasing my pressures on the PS2's to the same?
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Tyre pressures are specific for each car, due to options (weight from HiFi, electric seats etc.) and country requirements. For example, Germany has 3 sets of tyre pressures, normal load, fully loaded and high speed. Even the springs vary between 1Ms - this is the same for all BMWs. Best is to follow what is on your placard. Increasing power of your car does not require increased pressures as the static weight remains the same. In fact, increasing tyre pressure for road use without a corresponding increase in weight, reduces the contact patch area, therefore exacerbating traction problems with increased power/torque.
However, when using road tyres on the track, pressures should be increased to a certain point to compensate for the soft tyre wall of a road tyre - this helps reduce tyre roll when cornering. But you have to balance the effect of air pressure on the contact patch area with tyre wall support. This is where track tyres are beneficial due to their stiffer sidewall, therefore do not need as much tyre pressure as a road tyre, and you can concentrate on controlling pressures to maximise the contact patch area and temperature distribution across the thread.