Tire Pressure with non OEM Tire Sizes

[shark715]

I needed new tires for my '04 C4S Cab, and had a strong desire to install Michelin Super Sports as I have those tires on 2 other cars and think they are absolutely terrific. I find them to be very grippy (at least at warm temperatures) with good turn in, but without a bone jarring ride.

 

Unfortunately Michelin does not make Super Sports in my rear OEM size, 295-30-18.  I was going to go with Michelin PS2's instead as I've had good results with them in the past, , but no one had them in stock, and everywhere I called said they would likely not be available for at least a month.

 

After reading some of the other 996 posts here regarding tires, I decided to go with 285-35-18 Super Sports, but to keep the tire diameters the same, on the fronts I went with 225-45-18's rather than the OEM 225-40-018's.

 

Everything seems fine so far, but I'm wondering what pressures I should be using with the larger tires.  I did some calculations based on the maximum load of the OEM versus installed tires, and based on that I'm at 30 psi in the front versus the factory specified 36, and 40 psi in the rear versus the factory specified 44.

 

Again, everything seems fine thus far, but what pressure would everyone suggest I should be using?  I don't track the car, but on occasion I like to have some fun in the twisties and on entrance and exit ramps.  95% of the time the car is driven rather sedately.  I'd like to minimize the tire wear (despite occasionally playing Rodney Racecar Driver) and ride comfort is a priority too.

 

Thanks in advance for your help.

[shark715]

Aftet trying several different pressure combinations, I ended up settling for the OEM specs (36 front/ 44 rear) despite the tires not being OEM size.  Seems to be the best combination of handling versus ride quality.

[White987S]

I would suggest 36/40.