308 tire pressures

I have a 1984 QV 16 inch wheels Goodyear F1 tires same size as you 33psi front and rear and that is what label says on sun visor also in auto book.

 

I would run 4 or 5 lb over what the book says for a 308QV or 328. This will optimise braking and handling without being too severe on the bumpy bits.
I would think somewhere mid to late 30's would be somewhere on the money

 

I am using 32 front 33 rear with S03s on an 83 QV . Higher pressure in the front was giving a push. Still fiddling.

 

Our roads in Michigan are to rough for pressure higher than 33 PSI. In the spring I am going to switch from Goodyear to Michelin Pilot Sports have been told much better ride and handling.

 

jw6513,
Where did you get the wheels? Are they the aluminum Ferrari clones from Superformance in England? I am planning on getting a set and wondering how you like them?

How did you decide on those tire sizes? Seems a tad wide for the 7" and 8" widths of the wheels. I was thinking about using 205/50 and 225/50 front and rear. Can you post some pictures what what those tires look like on there?

Thanks!

Birdman

 

34 front 36 rear

 

Birdman,

As you have seen the car here... With the Etoile 16" rims and Kuhmo Supra tires using 35-36 lbs of pressure all around. Have played around A LOT with pressure and felt that this gave the best for SUMMER driving and good tire temps. Do not have enough data for winter/cold tires and cold road, though it seems to like a touch less pressure (will try 33 when i get back home). Therefore when it comes to winter driving, the jury is not out.

Enjoy the Drive,

Steven R. Rochlin

 

Start out one day with 36 PSI cold in both the front and the rear, then drive out to you favorite deserted road. By the time you get there you should be in the 39-40 PSI range warm. This is way too much pressure, but it allow you to find the correct pressure by releasing air.

Drive down the road at at least a brisk pace (8/10ths) and listen to the handling of the car. If the car oversteers, drop some pressure (1 PSI) in the fronts, if it pushes drop some pressure (1 PSI) in the back. keep working on one end of the pressure situation until you find the balance point where the car feels neutral. The difference in pressure front to rear is now correct; and what we need to find is the total amount of pressure for optimal grip.

Drive down the road again, feeling the amount of grip in the tires. There is a small pressure range where grip is optimized. One end of this range is characterized by quick reactions to steering input (higher pressure), while the other is decidely slower to respond to steering input (lower pressure). Decrease both ends of the car by the same amount of pressure (0.5 PSI) until you find the lower pressure end of the good grip.

Now drive to a gass station and add 1-2 PSI and see if the car is now centered in the sweet spot of grip. If so, drive home and let the car sit overnight. In the morning, go out and read the tire pressures and write them down. This is the cold pressures you want for that set of tires. Take the car out for a drive and afterwards, measure the tire pressures again and write these down as HOT pressures. Now you are equiped to A) find the pressures you car wants, B) set the pressures either warm or cold, C) understand how pressures are determined.

 

Mitch, excellent formated solution to the question.

 

I have the factory 16's with so3's on my '84308, I keep it at 33 to 35 all around at most.

 

For the street on my QV with the "upsized" tires, I use 32-33 all the way around as the warm pressure.

When I'm driving at the track, I'll usually run 36 in front and 34 in back (I want the fronts higher when I'm putting in hard braking and turning on a roadcourse).

Mike

 

Another data point: 34 all round on the street. 36F, 32R on street tires at the track on my GTB
Philip