Hot Rods That Same Old Question

Just changed the rear tires on my roadster, to coker classic radials 750R16. Put about 28 lbs of air. Doesn't seem to ride to bad and handling seems good but more testing needed. But the tires are bulging at the bottom should I put more air to make them look less bulging and will I sacrifice the ride and handling or improve it.

 

Try 32

 

what does the pressure rating on the sidewall say?

 

• Recommended PSI for 14 and 15" tires: 35 PSI. 16" tires: 40 PSI. Low air pressure can cause the sidewall to crack or lead to tire failure.
  

http://www.tiresandwires.com/Coker-Classic-Radial-750R16--Blackwall-Tire_p_75.html

 

that's what she said.......

 

Tire pressure ratings are designed for normal automobiles. A trick I have used for the last 45 years is to drive the car slowly across a concrete driveway. Stop and look at the dust pattern that is on the tread of the tire. If the dust pattern is all the way across the tread and down the side a bit then add air, a little at time, until the dust pattern is fully across the tread. If the dust pattern does not go all the way to the edge of the tire then let air out, a little at a time, until the dust pattern is fully across the tread. In this way you set the tire pressures for THIS CAR. If you travel and put stuff in the car recheck the pattern and adjust accordingly.
My roadster, weighs 2328 lbs, has 145/15s in the front at 30 psi. It has 255/70/15s in the rear at 18 psi.
This system has worked for me for 45 years and I have never had a tire problem.

 

I run 28psi in the 165's on the front and 18psi in the 285's on the rear. Been doing this for 29 years and I've had no problems. Even did an 8500 mile cross country road tripwith no problems.

 

I'd go along with the concept of running the pressure that puts a full contact patch on the ground and at what ever pressure worked to give the best ride, handling and even wear pattern.

When I first went to work in a Firestone store in the early 70's and we were just getting serious about selling radials we had guys come in with new (1972) cars complaining about the rough ride of the Firestone radials on the cars and every one of them had aired the tires up "so they didn't have that ugly buldge at the bottom" and quite often they had 45 to 50 lbs of air in the tires and one had 65 lbs in the tires because he said they didn't look right with the recommended 32. We actually did have a number of customers trade in the radials for bias Deluxe champions at the time because they were more concerned how the side wall bulge looked rather than how the tire performed. 40 something years later the same nonsense still exists, Guys still have a hard time dealing with the way a radial looks after they put them on.
That's not to say that I won't run bias tires as I will just to get the exact look I want on a couple of rigs in the fleet. That's a different situation entirely.