How do you determine what tire pressure to use on AFTER market rims like 19 or 20 inch rims? Do we use the pressure recommended by infinity cause our tires are lower in profile.

If I look at the sidewall it say 55max psi.

Im confused.

G35C 6MT / E55

 

I found this on sportcompactcar.com. Use this as a starting guide and adjust as necessary for driver preference, road conditions, modifications, etc.

(Vehicle Weight in lb/100) + 2 psi at heavier end + 2 psi all around if suspension and alignment are stock.

Example: Stock 911, 3,000 lb.
(3000/100) = 30 psi
Add 2 psi all around = 32 psi
Add 2 psi to heavy end = 34 psi at rear
With modified suspension, the result is 30 psi front, 32 psi rear.

 

Good info.

So I guess it is true, that it doens't matter you have low pro or different size rims, the tire pressure remains constant.

G35C 6MT / E55

 

Don't forget that a tire will increase about 6 lbs from fully cold to fully warm. If you really want to know correct tire pressure for ideal handling, May I suggest that you buy or borrow a tire pyrometer (instant reading digital thermometer). After hard driving, if the center of the tread surface is a higher temperature than the inner and outer edges, the pressure is too high. If the center tread is lower temperature than the edges, the pressure is too low. This tool will also allow you to compare inner tread to outer tread to properly adjust camber; and front to rear temps to adjust sway bars. With front to rear pressure differentials, you can compensate for handling balance with a given suspension setting. If you have coil-overs, this would be helpful information to adjust weight jacking. For those who have spent all their money on big wheels, and have nothing left for a pyrometer, may I suggest white shoe polish?

You can paint a stripe of white shoe polish accross the edge of the tread surface just extending about 1 1/2" down the sidewalls. Then scream around some corners. The shoe polish should be scrubbed off about 1/2" down the sidewall. If none of the polish on the sidewall is scrubbed, pressure is too high. If more than the prescribed amount is scrubbed; pressure is too low. Usually, on a performance tire, tread extends over the edge onto the sidewall a bit. You never want to see scrub marks extending past this point. The shoe polish just makes it real easy to see.

One thing to keep in mind, is that with a front engined car like a G, it is hard to achieve perfect balance in stock trim. The above tests will be more valid for the front tires; you mave never get the rears up to the temps (or side wall rollover) of the fronts. Set the fronts, then keep the rears a few pounds lower for ideal handling.

04 G35 6MTS Aero Kit/Nav/Prem/Wint (Hopefully Sept 03)
Warning: Objects in Mirror Are Losing!