I have just fitted a set of Excelsior Stahl Radail tires to my Model A coupe,this has made a unbelievable improvement to the handling , the car weighs around 2600 lbs, Running 6:50-16 on the front and 7:50-16 on the rear I can't find any tire pressure recommendations,so I'm asking if anyone running a similar deal,what pressure front and rear are you running
According to the Antique Tyres catalog-Aussie Dealer for Coker and others- your 6.50x16 are rated at 1580lbs@35psi and the 7.50x16 are rated at 2150@41psi. These are the design figures for your tires. I'm running American Classic radials on my 32 coupe which weighs 2850lb due to a very heavy Poly engine. They are rated about 400lbs less than the Excelsiors at 35psi and I run them at 30 psi. Try 30 and 35psi respectively and keep a close eye on tire wear- should be easy with no fenders LOL
I know coker say 41 psi Due to heat build up. I cant imagine running 41 psi in a light highboy giving a very pleasant ride , we run ours at around 30 psi , still gives the old kidneys a decent shake up .
If the tires are rated @ 1500 pounds as mentioned, your curb weight is half that per tire (tyre ). You can air 'em up with low-ish pressure because at your weight, you won't get as much flex and heat build-up. I can't give you an exact pressure number because then I would be practicing engineering without a certification.
I have mine mounted without tubes but haven’t run them yet. I know there are plenty of guys running them without tubes. The rolling bones guys run them without tubes if my source of information is correct. And they run their cars hard and long distances too.
I have 5.00x16 Excelsiors on the front of my A Pickup and run those at 32psi. I have 7.00x16 rear Excelsiors and run those at 25psi. I have over 6,000 miles on them like that and there is no visible wear that would indicate that they are not properly inflated.
I imagine coker classic bias look radial would be the same pressure as excelsior for a same size tyre.
One way to think about it is the percentage of the rated max that you have on each axle. Making up numbers, if your two tires on an axle are rated for a total max of 2000 lbs (1000 each) at 40 psi and your weight on the axle is 1200 lbs, you would put 1200/2000 = 60% of the max rated pressure in each tire, or 24 psi. Again, the concept is real, but I made up the numbers for the example. This method results in the proper tire footprint and wear based on the load. Use it on my 13,000 lb RV with good success.
I have a set on my Model A pick up hot rod. Right now I can't remember the pressure I run them at. But it's not much. I just start high and then start backing the pressure off until you can see the tire is using as much of the tread as possible. If you get too low the tire will start rolling over while cornering so you want to think about that. Also I usually have more pressure in the front than the back. Anyway, that's what I do. I think it helps the ride on light weight hot rods to do this.