I’m wondering what you guys are running for air pressures on your bias plies and what tires front/rear. I’m running Coker classic bias plies on my 40 Coupe. I normally run 27 front and about 23 in the rear. I don’t remeber how I got there but I was just thinking about it and thought I’d see what others are running. So if you want to chime in post your front/rear pressures,( bias plies only please ) and what type of vehicle they are on. Thanks
Lots of factors, the weight on each end being a good thing to know. You also need a bias air pressure gauge.
tire wear in the center of the tread will show if it has too much...but....all bets are off if >> a lot of hotrods run a tire that is meant for a wider rim, which will wear out the centers. I run my 32 really low in front at 20 for just one reason...it has a super fast ratio box, and running them lower gets rid of the go-cart twitchiness caused by that very fast ratio...... Two and a half turns, lock to lock! my rears at 24...if I go more, I feel some more "handling sensitivity" because there is no weight back there, compared to your 40 coupe. In other words, we rodders run big rear tires, made for more weight, so if a car body style like mine that has little weight for a big tire , we really need to lower the pressure, IMO .
At first I was running around 20psi... had some shaking around 55-60.. Upped all of them to 32 and took about half the shake out of it.. balancing took the rest of the shake out of it. Sent from my iPhone using H.A.M.B.
I agree many factors in play but I doubt many guys actually have scaled their cars. I use a Longacre gauge left over from my dirt racing days. It’s 0-30 in 1/4pound increments. I’m just trying to get an idea what guys are running Front/Rear in similar cars. I understand another 40 Ford Coupe won’t scale exactly the same as mine, but the front/rear weight is likely similar. Every time I fill with fuel and luggage for a long trip like I’m taking this weekend adds a good bit to the rear weight, I should probably add a bit of air to the rear for that but I never do.
I am running 26 in the front 500/525X16 and 23 in the rear 750X16 tube 'Stones on my '32. I know what the car weighs, and worst case is just under 3000 lbs with two people, full fuel etc. The pressures are based on tire max ratings with actual axle weights, backed up with even tread wear and cool running.
When I was installing bias tires in a Firestone store in the early 70's we normally put in 28 to 32. We may have run 26 on cars belonging to people who expected a softer ride. Still as some of the guys said, it is a vehicle to vehicle deal with modified cars with different tire and rim widths. I think I ran 26 in the F and G 70's on my 69 Cutlass with 7 inch rims. Any more caused center rib wear on it. I don't remember what I ran in the N50 14 on 8-1/2 inch rims on my 48 but it wasn't real high.
For what it's worth, tire pressure gauges aren't necessarily very accurate, or precise. Some years ago I brought in two identical dial gauges to a friend who was working in a calibration shop. One gauge was within one psi over its whole range (10 to 60 psi), while the other was ten psi out over the whole range. My friend repositioned the pointer on the bad one to fix it. We often hear about how important it is to run correct tire pressures, but it's pretty difficult to know if the gauge is accurate. The notion of comparing the gauge to a "known good gauge" has obvious flaws, it would be a neat idea if a chain of gas stations or parts stores had a certified, calibrated test station for their customers, that was regularly certified much like weigh scales in grocery stores are. One can't rely on a gauge to be accurate just because it is very expensive, if it was dropped before you got it, it may now be inaccurate. I always run bias ply tires at 32 psi, same as radials.
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