The Stovebolt Site Forums The Parking Lot Big Bolts Tire Pressure for split rims

I finally got a couple of the 20 inch 6 bolt lock ring rims needle scaled, painted and put back together with new tubes and a decent tires and aired up to around 30 psi. Everything has gone well so far but I saw the radial tire was labeled for a 85-90 psi and though I would ask the group before filling them beyond 40 psi.

I thought I had read somewhere, maybe an OSHA brochure not to fill these rims beyond 40psi.

What is the correct tire pressure?

Thanks
Dan

When I bought 6 new tires for the 48 2 ton I had the dealer mount them on the wheels I had cleaned and painted.
He said not to go over 75 lbs.
Tires are rated to 120 lbs.

Under-inflation is about as bad as too much pressure. If the wheels are in good condition and lock together properly, more pressure just makes them lock more firmly. If they are in danger of separating because of wear and/or improper fit, they shouldn't be inflated at all.

Keeping the pressure low will actually increase the risk of a wheel coming apart from rubbing a curb or hitting certain kinds of bumps since the locking system relies on adequate tire pressure keeping the pieces from being dislodged from each other.

Obviously, RH-5 widowmakers don't need to be inflated at all- - -that tiny locking lip is just too susceptible to minor damage, wear, or rust causing an explosive separation.
Jerry

If the tire is labeled 85 to 90 psi, that is what you need to run. Less than that will cause the sidewalls to flex, generate heat and ruin the tire.

Thanks for the input, I need one more rim and I can retire the widow makers. The guy at the tire shop said they make great grills or fire rings.

The pressure marked on the tire is amount needed to get the maximum load bearing, not the normal operating pressure.
The tires on your pickup may say they are rated for 1874 lbs of load at 45 lbs pressure, but the recommended operating pressure is 30 lbs.

Are you sure about the 30 psi? I remember inflating my pickup and car tires to 30-32 psi and it was rated on the tire. GMC recommends tire inflation on my 2008 2500HD Duramax pickup at 60 front and 70 rear and the tires are rated at 75 psi. Once again it is rated on the tire.

I am changing the rims over to 20 inch 6 bolt stud centered Budd rims with lock rings and agree that operating with under-inflated tires can lead to premature tire failure.

I agree with Jim Sears. Tire pressure is a function of load. In sports car circles they say that tires should gain about 3 psi after running a few miles.

My rig carries 6,000 lbs on the rear and 3500 lbs. on the front. If I inflate the E-rated front tires to 80psi listed on the sidewall, it rides rough and handles miserably. I run 36 ft. and 70 rr. when loaded.

Last weekend I drove it pulling a utility trailer 250 miles, left the trailer and came back empty. I was too lazy to drop the pressure on the rears and suffered from poor lateral stability. The saving grace was the trailer acting as "drouge" and keeping things going straight. Coming back empty it was a lot more work to drive. I almost stopped to drop the tire pressure to about 36 on the rear but then the road improved and I just suffered with it till I got home.

1Ton_Tommy is 100% spot on. Too many tire guys don't have a clue. I run my pickup (don't scold me for driving an F250) at 70 front, 45 rear unless I load it. When I get an oil change I always have to let 10 out of the front and 35 out of the rear because they go to max inflation, which makes it ride like I'm bouncing on basketballs. All 4 of my tires are almost worn out and they are worn evenly across the tread.

Most tire blow-outs you see are from underinflated tires - severely underinflated, not within recommended guidelines. Note how your tires say "MAX" inflation pressure? There is a minimum as well.

On my old F-250, with the 7.3 power stroke.
When empty, I run 65 in the front and 50/55 in the rear, but also carry a 30 foot, 3/4 inch chain in the very back to smooth out the rear some.
Probably about 300#.
When loaded, fronts 75 and rear 70+ depending on the load.
Tires are rated max. pressure at 80 psi.

Don

Thanks for the input. When I get it on the road I'll set them at 35psi and take it form there. I don't need a bouncy ride since this model does not have shocks.

You need to re-read Hotrod Lincoln and Crenwelge posts on page 1, you have split rims, not one piece tubeless...BIG DIFFERENCE!

Be safe,

Mike B

Yep, don't skimp on the air pressure.

For truck tires I usually start out at the recommended pressure on the sidewall and if lightly loaded and as needed for comfort reduce the pressure a little. Keeping an eye on how they look and wear and keep enough air in them so they always look tall and proud and never wear the outside of the tread first.

Grigg

The old rule of thumb we used for tube type tires on multi-piece rims was if the pressure of a tire was more than 10% below the recommended pressure, we did not attempt to air them up- - - -break it down and find the leak! Attempting to add air to a low tire could possibly cause an explosive rim separation. My employees knew that was a good way to get fired.
Jerry

Jim isn't really meaning any specific truck, only using those numbers as an example. However, there are real world example that have cold inflation pressure for a given tire size/load rating installed on the vehicle that are not the same as the maximum pressure listed on the sidewall. Example, '98 Chevrolet K1500 with a 245/75/16 LT E lead range. The tire is marked for 80 psi max, however, the vehicle spec is 45 psi cold. Same year, make, model truck with the P rated option tire, which is rated anywhere between 35 to 41 psi depending on brand, runs 35 psi. Obviously, using different size or load rating tires will change what pressure should be run.
Admittedly, there are times that the "engineers" get it wrong, and specify a pressure that is too low. remember the Ford Explorer?
On the not inflating over 40 psi part, that's for seating the tire. Once seated, it can be set to whatever the cold pressure for the tire should be.

Does everybody need to be reminded of the original question- - - -"TIRE PRESSURE FOR SPLIT RIMS"? My concern is that someone who does not understand the physics of how a split rim holds itself locked together will reduce the pressure to a dangerous level and hurt himself or someone else. If he chooses to do so after the danger of reduced pressure has been explained, Forrest Gump's Mama had a saying about that person! (and it wasn't "Life is like a box of chocolates")
Jerry

Bill,
That brought back alot of Memories...Roadway Express
At the height of that Mess We had a 28ft. pup Spotted at every Firestone dealer on Long Island Just to Cart the takeoffs away,GOOD or BAD.
Fill it up,spot another.
Many trailer loads back to Firestone,MUCH overtime.
steve sr.

Jerry,
You are So Right and Your rule of thumb is the correct and SAFEST Way to be.
Err on the side of Caution.
Improper Servicing techniques/procedures is what usually gets Most so called techs Maimed OR Worse.
regards always,
steve sr.