Tandem axle--tire pressure?

[bscott]

Any suggestions for tire pressure for 14" Carlisle bias ply tires on a newly installed tandem axle?
I ran 60# when it was a single.

Bob

[kmclemore]

Well, it's hard to say. Some will say just put them at 60# and don't worry. My suggestion, however, would be to do what I used to do with my tires when racing... chalk the tread on all the tires and take the trailer for a drive... after about 20-30 minute's drive at normal speeds, check to see where the chalk is worn off... if it still is evident on the edges, the pressure is to high... lower the pressure till driving just removes the chalk from the edges of the tires. After you've finished the drive, also check the tire temperatures... they should feel mildly warm, but you should be able to easily hold your hand on them... any hotter than that, add air.

[Oskar 26M]

Thanks for the chalk tip K. I've been trying to figure out a way of judging optimum tyre pressure ever since I upgraded my single axle trailer to a higher weight/load rating. Its new tyres are rated to take their max load at 95 psi. The tyre dealers have given vague advice that this pressure would probably be too high for most running loads but no one has come up with a simple method of on-road testing. I'll buy some chalk and give it a try.

[Hamin' X]

Just a note on the chalk tip: Tandem axles pivot on a center between the two axles. When turning, the edges of the tires get scrubbed. The chalk tip is only valid on tandem axles when running in a straight line and the trailer load is evenly distributed between the axles. This weight distribution is why the trailer tongue height is so critical on tandem axles. Too high and more load is carried on the rear axle and too low, more weight is carried on the front axle.

~Rich

[Kelly Hanson East]

YOu are probably over thinking this Oskar. Unless you are really heavily trailering, your tire life will be probably be dictated by rot and sidewall failure rather than by tread wearout - ergo you can run them anywhere near/at the max pressure which will give the least rolling resistance without adversely affecting your operating costs.

My 2002 tires are on their last season due to sidewall rot - tread is fine. Trailered about 2000 miles per year approximately.

[Oskar 26M]

True KHE, I am probably over thinking this
But I think I'l take the pressure up closer to the max. I'm not too worried about tread wear, but do get concerned about stressing the side walls through under inflation.

Thanks all, for the advice

[Hardcrab]

I've just done some research on replacement tires for my truck, and I learned that a single tires "load rating" goes down when used as half of a dual tire setup.
At least as duals on a single axel.
I don't know the logic behind this, or if it might also apply to the dual axels on trailers.

I would argue that one should not inflate a cold tire to the max as listed on the sidewall, because the increase in pressure when the tire gets hot will exceed that max and might cause all kinds of grief.
At least drop the pressure back down to max after it's run for awhile, and then use a cold reading as the correct cold pressure in the future.

[Hamin' X]

I would argue that one should not inflate a cold tire to the max as listed on the sidewall, because the increase in pressure when the tire gets hot will exceed that max and might cause all kinds of grief.
At least drop the pressure back down to max after it's run for awhile, and then use a cold reading as the correct cold pressure in the future.

The Max Cold Pressure rating on the tire is designed to account for the increase in pressure when running. If you decrease the pressure when the tire is hot, you will be running the tire under-inflated.

~Rich

[Kelly Hanson East]

This is worth restating. You never bleed air from your tires when they get hot to compensate for the increase in pressure.

Set your tire pressure when the car has been sitting for an hour and the tires are at ambient.

After running for one hour at 60 mph in 90F weather, my tire pressure goes from 50 psi to 60 psi and stabilises there, for the record.

[MadMacX]

Trailer tires are, by design, supposed to run at high pressure, so put them at 50-60 lbs., cold, and check for heat after 25-30 miles of highway driving. Like previously stated, if the are too hot to touch, add air, if not, leave them alone. BTW, life expectancy of trailer tires is only about 2-3 years, regardless of amount of thread showing.

More info; http://www.discounttire.com/dtcs/infoTr ... eFacts.dos


Regards,
Pat

[bscott]

Pat, thanks for the link.

Bob