hi all, last week end i have had a great surprise. after filling gas, i went to tire pressure station. then, as i did not remember the exact official pressure, i put something like 10% more. (2.6 bars vs 2.4 on my old TRX). then the surprise was one of the best : the car was transformed : very light steering, light sensation, more agile ... I should notice here that my car is a 3.2, without powered sterring. T owners dont have the same problem. I put this subject so that people can leave here their experience. If You did not even try that, I encourage You to try and drive. I think this is partly due to old age of my TRX. Anyway, I have been driven all day long at a meeting, and did not mentioned any loose in grip. Soon I will mount my new "eagle like" nexen (roadstone) tires. I will probably make tests with different pressures.
I believe the more agile sensation you are feeling is the tire crowning in the center. Having less of a contact patch on the road will certainly make the car easier to steer and when not pushing the tires to the limits also make the car a little quicker to respond. If you were to drive the car on a track and push the tires you would probably notice the loss in traction. On the street the most noticable effects are going to be the tires will wear in the centers premature and the ride will be a little rougher. If you know someone that has a infrared pyrometer you can push the car through some corners and measure the tread temps near the edges and center and you will probaly notice the center to be much hotter due to the increased tire pressure. Racers use this technique to find the right tire pressures to run since the pressure increases as the tires get hot we have to set them low to start. On the Mustangs we start out at 23 PSI and the pressure when we come off the track is around 30 psi when the tires are at operating temps. The temps across the tires from inside to outside will tell us if we have an even contact patch. If the temps are not even across the tire we will adjust starting pressure or make alignment adjustments if needed.
I also keep my tire pressure high. 35-40psi on a 308QV with larger aftermarket wheels/tires. It really lightens up the steering, and reduces rolling resistance, so acceleration is better. I'm sure it isn't optimal for handling, but for road driving it's fine. It helps with all the tight, slow speed turns I have to do to get into the garage. Plus, it makes it a lot easier for my wife to drive. My commute is short, and with only 1K miles per year, the tires with dry rot before I have any uneven tread wear problems.
Every tire manufacturer,installer and or seller will tell You "inflate Your tires to the psi recommended by the vehilce manufacturer." Your tire size and pressure is designed for the weight and suspension of the vehicle. Tire Rack will tell You when You purchase aftermarket tire/wheel combo's to inflate the tire per vehicle manufacturers specification's. I don't think They are making this up, I wouldn't let My pressures be more than a pound or 2 away from the manufacturer specs.
