Tire Pressure Recommendations

[Beisentrout]

I recently competed a mechanical restoration of my 1970 911T. It has new Pirelli CN36 185/70-R15 tires on 5-1/2" steel rims, Koni shocks, bearings, ball joints, tie rod ends, half shafts, and torsion bar bushings in addition to a rebuilt engine and transmission. A suspension shop recommended by my mechanic finished the job by replacing the rear torsion bar bushings and doing a corner balance and four wheel alignment. I was surprised to see that they set the tire pressure to 28 psi front and 34 psi rear, so I checked the operator's manual and it specifies 26/29.

The ride seems harsher and noisier than I remember, but I have not driven it or any other sports car for 30 years. Am I a victim of a poor memory and expectations formed by modern seats and suspensions? Have years of experience and material upgrades changed the recommendations on tire pressure? Am I likely to find the ride better by returning to the original tire pressure recommendations? I'm seeking advice on how I should adjust my expectations and/or tire pressure for street driving that will rarely rise to the level of "spirited".

BruceE

[edmayo]

Lower the pressures and see if it helps. I like them better set higher. but you may not. Easy enough to try.

[Arne]

No harm in trying them at the factory pressures. I don't think I'd want to go lower than that, however.

Actually, since you are running them on 5½" wheels, the lower factory pressures may work better since the tires might not "crown" as much.

[72targa]

Bumping this older thread as I was looking for a reference. May help others.