Q: Will lowering tire pressures help over bumpy surfaces?

Q: I am driving a 2000 Porsche Boxster S at Porsche Autocross events and when I drive my Boxster over a bumpy section my Traction Control comes on and slows my car. I don’t have a switch to turn off the TC. To help with traction should I lower the tire pressure? Would raising the rear spoiler help with this issue as well? The spoiler raises at 75 mph but I can raise manually.”

A: I want to answer by saying, “Give it a try!” That’s actually the best answer because there’s never one perfect solution that will work in all cases. If the only thing I could do was adjust tires pressures, and I wanted the car to absorb the bumps better, then yes I’d start by going lower on the pressures. If that doesn’t work, I’d go the other direction and see what happens. It’s possible that adjusting tire pressures will not be the solution, though. And it’s possible that lower pressures will help over the bumps but hurt elsewhere – and you need to figure out whether the compromise is worth it.

Also, I’d suggest making some fairly large adjustments – like 4 psi at a very minimum, and even more like 6 psi (or more). Make a big change to find out if it helps. If it’s heading in the right direction, then you can start fine-tuning with smaller adjustments. At first you’re just looking for a direction – is it helping or hurting?

As for aero with the spoiler, why not? In any autocross, I doubt that you’ll ever be hurt by more downforce – the straightaways are not long enough for the aero drag to be a negative. So give it a try. It’s possible that you won’t feel much of a difference, but there’s only one way to find out. Go for it – and learn.

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