Trailer Tire Pressure

[Terra Firma Scott]

I should know this but dont. I have a 12K GVWR utilty trailer 18 ft with dual 6K axles. I have the trailer loaded to Max rating (10k in load and 2k in trailer weight). Should I inflate the tires to the max load spec on the sidewall of the tire? 80 psi cold? sounds high...
What yall think?

 

[crbr]

I should know this but dont. I have a 12K GVWR utilty trailer 18 ft with dual 6K axles. I have the trailer loaded to Max rating (10k in load and 2k in trailer weight). Should I inflate the tires to the max load spec on the sidewall of the tire? 80 psi cold? sounds high...
What yall think?

I'd follow the recommendations on the tires. Eighty psi is not high with the tires, if in fact they specify 80 psi on the tire. It's OK. I'd rather be on the specs than to be under inflated (with a load) and have the tire heat up and fail.

 

[Bird]

Yep, Scott, I agree with crbr.

 

[DieselPower]

What does the trailer data plate or owners manual list? Just because the tire's max pressure is 80 PSI doesn't mean that it should be inflated to that. What are the rims rated at? It's not uncommon to find load range E tires that go up to 80 PSI on rims that are only rated for 65 to 75 PSI. What is the max load rating of the tires in pounds when inflated to max pressure?

A over inflated tire will wear prematurely on the middle of the tread and will also be very bouncy.

Not saying they shouldn't be inflated to 80 PSI but I would check the rims and any trailer manufacturer spec's first.

 

[Terra Firma Scott]

The trailer id plate doesnt specify tire pressures.Nothing on the rim either..All I can find is on the tire itself..Load range "E" Max load single 3100lbs at 80 psi cold...total of four tires on trailer.They are Dexter axles with 16 inch steel 8 lug rims no spokes but solid....Thanks guys! they are currently at 55 and ill Probly set them to 75 or so here in florida its real hot and im sure they will increase in psi once warmed up..

 

[skipmarcy]

The trailer id plate doesnt specify tire pressures.Nothing on the rim either..All I can find is on the tire itself..Load range "E" Max load single 3100lbs at 80 psi cold...total of four tires on trailer.They are Dexter axles with 16 inch steel 8 lug rims no spokes but solid....Thanks guys! they are currently at 55 and ill Probly set them to 75 or so here in florida its real hot and im sure they will increase in psi once warmed up..

My 14k utility and 12k dump have no tire inflation info either, can't recall ever seeing it on a trailer DOT tag. All of my tires are E range tires and call for 80 psi max. and that's what I keep them at. Both trailers are seldom used at much less than full loads anyway. That pressure rating is for a cold tire and it should say so - pressure increase from heat is already calculated into that rating. You should never try to accurately measure tire pressure on hot tires. Even just the sun shining on one side of your trailer in the morning for an hour will throw the pressures off as much as 15 psi. from side to side. I always check my tires when I know they've been stabilized out of the sun for at least a few hours, preferably early in the morning. I ran my trailers in Florida pretty much 5 to 7 days a week for a couple years following what I have just described - and several thousand miles of interstate driving at full loads and I have had excellent treadwear on both the bias ply and radial ply tires. As far as rim ratings, I'm not as familiar with those as I am tires. I'm sure the original rims on a trailer such as mine or yours would be rated for E range pressures. As with most everything else with ratings, like hitches etc., there is quite a bit of fudge factor figured into those ratings. I doubt 80 psi on a rim rated for 65 or 70 psi is truly dangerous. I would be more worried about running the tire too low than the rim too high.

 

[Bird]

I was assuming (yeah, I know that can be a mistake) that 6,000 pound axles would have the right wheels for those tires. And apparently they do. I've never seen a data plate on a trailer that gave tire pressures; only axle and gross weight capacity, although some trailers may provide that data. However, I assume (again) that wheels still have a code stamped in them somewhere that tells what maximum weight or air pressure they can handle.

 

[jbrumberg]

Trailer tires do not need to be inflated to maximum pressure as stamped on the sidewall. High capacity trailer tires do not need to be at full pressure. Make sure that the maximum capacity for the tires as stamped on the sidewall is equal to and/or greater than the load being carried divided by the number of tires. Jay

 

[Skyco]

I would hope that OEM supplied tires and wheels are matched for rim capacity vs tire capacity, but then again who knows....

My 16" G rated dump trailer tires say 110 PSI on the sidewall and that's what I run them at when loaded to 14,000 lbs. They squat pretty good at that weight, which isn't far from the max rated load for each tire...any less than 110 PSI for that tire at that weight and you are stressing the tire.
I have one of those IR temp guns- they can be really useful for measuring tire temps, if too hot go up in pressure, but not to exceed the max sidewall marking. They'll also show you a hot running bearing.

Here is a pretty good chart for tire pressures vs load for many common tires-http://www.goodyear.com/rv/pdf/rv_inflation.pdf

 

[jbrumberg]

Skyco:

Thank you for the tire pressure chart. It is a lot more informative than the one I use. I also like the idea of an IR temperature gun . Jay

 

[Skyco]

Yeah that IR gun is really handy, when towing I routinely shoot the tires and hubs and even the brakes. A hot tire compared to the others means something is wrong- usually low air, maybe picked up a nail or whatever. A hot hub may mean a bearing is tight or grease is bad etc. Where it really helped me out though was balancing the brakes left to right on my dump trailer. Had some swing to one side under heavy braking- so is the side that swings out got an over eager brake or does the other side have a weak one...comparing temps after some long downhill braking loaded heavy it was easy to spot the offender and adjust it. In my case it was one brake not doing enough, 5 minutes under the trailer with a screwdriver through the brake adjusting hole and it was fixed

There are even some ideas published to check the tread temps across the face of the tire, they should be even, if the center is hotter you may have too much air, if the sides are hotter you may need more air...