Depends on a number of factors, including your own preferences. E.g. depends on whether you are driving in city or highway or on a track. In general I personally would keep the pressure well above (maybe up to 5 psi above) the stock figure for the SX4. The reason being that these low profile tyres are susceptible to damage on bad roads, and could expose the alloys as well if the tyre pressures are too low. I wouldn't even think of ride comfort. If you are looking for performance the higher tyre pressures will help while cornering hard and improve tyre life; they might reduce grip a little bit, but I think you have much more than enough grip with your tyres. In wet weather, the grip might come down if the pressure is too high and there is a possbility of aquaplaning; I don't know about the wet weather performance of your tyres.
To a certain extent your choice would also depend on rim width. If you have wide rims (say close to the upper limit for your tyre size), you can afford to lower the pressure to a certain extent as the tyre sidewalls will not flex as much; ths is from the performance, tyre life and grip point of view. But I personally wouldn't lower too much, keeping in mind bad roads and possible tyre/wheel damage.
If I were in your shoes I would start with 5 psi above stock (or something like 35 psi) and then experiment, depending on my requirements.
Last edited by rks : 21st July 2007 at 10:55.
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