Originally Posted by Boom vang

Go by what the car company suggests. Tons of research has gone to what is the optimal for the best handling

The number on the sidewall is the maximum that the tire will allow but is not the optimal for your car. Because all cars are different weights the pressure has to be adjusted accordingly. Imagine if our car was 1000lb lighter our pressures would be much lower for the same size of tire.

Higher pressure does not equal better handling. F1 cars have a pressure around 8 to 14psi.


By adjusting pressures you can dial in more understeer or more oversteer

Running at very high pressures will have a much harsher ride.

Originally Posted by drexappeal

I understand why MB recommends a pressure that is much lower than the max and also understand that it is probably better for handling, however, if a person is looking to sustain say 19 tires that are very expensive...having a lower tire pressure may not be the best choice. Yes, you'll get better handling, but is it worth having to buy new tires more often?

Plus, since I'm not on OEM tires anymore, adjustments needed to be made.

Originally Posted by Moviela

The pressure listed on the side of the tire is the MAXIMUM for that tire. It is usually much more than the running pressure. If you over inflate your tires, they will wear faster in the center. If you neglect your tires, and allow them to run under inflated the edges will wear faster. Properly inflated tires will run cooler, with greater gas mileage. There are exceptions to the placard values, and they are explained in the manual.

A digital pressure gauge is not more accurate. A calibrated gauge is more accurate. Most digital gauges cannot compensate for altitude pressure variations. A $ 30 Flaig gauge is perfect for the glove box. They are German made, read in Lb/sq-in and Bar, and are available from our sponsor Performance Products. I have used this gauge for ages, and they remain accurate for decades. With the price of a set of tires around $ 1,000. one of these is very cost effective.

http://www.performanceproducts.com/p...aig+Tire+Gauge

You can increase the life of your tires and rims by not filling them with air. Nitrogen is in tires of aircraft, race cars, and Costco shoppers. Look for the green valve caps, those tires are filled with inert Nitrogen.

Originally Posted by Boom vang

Agreed that adjustments must be made but running at 40 /44 seems way too high.

You could always do the chalk method of determining the correct pressure, and old racer trick

Originally Posted by c230K415

what's the chalk method?

Originally Posted by rtking

This is an autocrosser's trick. You use chalk or white shoe polish on the shoulder of your tires. Then drive as aggressively as you normally would. If you are rolling over too far into the sidewall, the chalk or white shoe polish will have worn off and you will know to add more tire pressure to help reduce sidewall deflection.

On my C230 Coupe, it's recommended to run 28 psi front, 32 psi rear. Since I feel that there's already too much understeer stock, I ran 32 psi all around. But since installing John Goodlad's C32 sway bars, I've increased the tire pressure to 35 psi all around.

Bob