TT Air pressure

[oldtanker]

I upgraded my TT tires from some Chinese? brand 205/75/14 LRC to Goodyear Endurance 205/75/R14 LRD. Trailer states 32lbs tire pressure, new tires have cold pressure 65lbs. Di have to stay with what the trailer states or can I go higher? And if so how much?

Thanks, Bob


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[JIMNLIN]

op wrote:
But how low is too low?? Is there an intermediate sweet spot? I would be interested to see if anyone has any authoritative data on that issue.

Having five commercial trailers on the road with 28 tires on the ground 24/7 for over 11 years I've found out the hard way derating heavy tires like a E to 65 psi (D to 50 psi) did in fact lead to hotter running tires and premature failure down the road.
Yeah my truck tire dealer warned me not to derate them that much but being young and dumb and thinking he didn't know what he was talking about...I found out he was correct.
I don't over tire a trailer now which allows me to use max pressures plus using LT tires on all my trailers I don't have tire issues anymore.
Lots of tire blogs out here on towable's (trailers) all saying basically the same thing.....
I like this one for those that have over tired their trailer.
rvsafety.com
Tire Load and Inflation Ratings

Note: Towable – Travel Trailer/ 5th Wheel owners Due to the severe use conditions experienced by tires when axles are very close together – tire industry experts recommend maximum (sidewall) inflation pressure for towable tires unless this causes a sever over-inflation situation (20psi+), often referred to as the ‘basketball effect’. If this is your situation allow a 10 – 15psi safety margin above the minimum required inflation pressure.

[rbpru]

Unless the manufacturer has a recommended pressure for the tire load, most folks run them at the highest pressure.

Just like your car, if you run at the highest pressure you get a rough ride and tend to wear the centers out of the tread. On a TT you do not notice the rough ride except to the increased jostling of the stuff inside, and it is unlikely that you will tow enough mile to notice significant center tread wear.

The only safety advantage is if the tire pressure drops a few lbs, chances are you will not be running above the tire's weight rating.

Usually the weak link in the chain is the axel rating. If your tires have a total load rated that is 200 lbs. over the axel limit. How much do you gain having them rated 300 or 400 lbs, over the axel rating?

You buy a premium tire for their reputation for quality. You have more confidence the tire will do what it is supposed to do, if you follow the tire maker's recommendations.

Good luck

[93Cobra2771]

allenm wrote:
I also have Goodyear Endurance ST20575R14D tires on my 3,750 GVWR Jayco. I've been thinking about lowering my tire pressure down from 65 psi. My problem is bouncing, especially on concrete interstates.

If I subtract 12% to account for hitch weight, I'm down to 3,300, which would be 1,650 per tire. Goodyear's Load/Inflation table for these tires shows 45 psi will carry 1,640 lbs. I'm thinking of going down to 50 lbs to see if that helps on rough roads.

For what it's worth, my trailer has a Lippert 3,500 lb single axle. I think these lightweight single axle trailers are prone to bouncing on rough roads.

https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

One factor to keep in mind is that as pressure goes down, tire temp goes up (this from a tire engineer). Take two comparable sized tires, say one D and one E rated. Air the E rated down so it can carry same load as the D rated (using tire tables). The E rated will run hotter than the D Rated. Heat is one of the big enemies of tire life.

You might try dropping perhaps 5psi, but I wouldn't want to drop all the way down to 50. Especially if you haven't actually scaled the TT. I would value tire longevity over trailer ride any day of the week. That's just me, though.

[profdant139]

Allen asks whether we can go lower than 65 with the Endurance, to reduce bouncing on rough concrete highways. Good question! My fear is that by reducing tire pressure, we increase the chances of the tire overheating -- the lower pressure causes the sidewall to flex, and the internal friction heats the tire.

But how low is too low?? Is there an intermediate sweet spot? I would be interested to see if anyone has any authoritative data on that issue.

In the meantime, I run them at 65 and just put up with the bouncing.

[mike-s]

goducks10 wrote:
Browse around on this site and show me a tire that has a load rating lower than 50 psi. Sure you can run lower. But as you know TT/5er's come with tire stickers that tell you to run the max sidewall psi.
http://www.tredittire.com/tires

Easy. Every single one of them. Load/inflation tables are standardized across the industry. Perhaps you mean "maximum pressure rating," but that's not what you're saying.

[trail-explorer]

goducks10 wrote:
First off there's no ST tires in that size that uses 32 psi. The lowest is 50 psi.

Ditto.

And I've never seen an RV manufacturer state what tire pressure to run at.

[JIMNLIN]

Some years back some ST tires came with a B load range and a 32-35 psi rating. If the OP has those tires they are old. The OP stated his trailer says 32 psi. Not knowing how heavy his trailer is per wheel load a 65 psi tire may or may not be the best idea.

Most of the time upgrading tires on a trailer is a good idea to a point....just keep in mind you don't need a load E tire when a C load tire has plenty of capacity.

[goducks10]

mike-s wrote:

goducks10 wrote:
First off there's no ST tires in that size that uses 32 psi. The lowest is 50 psi.

Nonsense. For ST205/75*14, the load tables show 1300 lbs @ 30 PSI, and 1430 lbs @ 35 PSI. Manufacture's can interpolate the tables.

If the OP will post his TT model, we can see how reasonable the numbers are.

Browse around on this site and show me a tire that has a load rating lower than 50 psi. Sure you can run lower. But as you know TT/5er's come with tire stickers that tell you to run the max sidewall psi.
http://www.tredittire.com/tires

[allenm]

I also have Goodyear Endurance ST20575R14D tires on my 3,750 GVWR Jayco. I've been thinking about lowering my tire pressure down from 65 psi. My problem is bouncing, especially on concrete interstates.

If I subtract 12% to account for hitch weight, I'm down to 3,300, which would be 1,650 per tire. Goodyear's Load/Inflation table for these tires shows 45 psi will carry 1,640 lbs. I'm thinking of going down to 50 lbs to see if that helps on rough roads.

For what it's worth, my trailer has a Lippert 3,500 lb single axle. I think these lightweight single axle trailers are prone to bouncing on rough roads.

https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

[mike-s]

goducks10 wrote:
First off there's no ST tires in that size that uses 32 psi. The lowest is 50 psi.

Nonsense. For ST205/75*14, the load tables show 1300 lbs @ 30 PSI, and 1430 lbs @ 35 PSI. Manufacture's can interpolate the tables.

If the OP will post his TT model, we can see how reasonable the numbers are.

[goducks10]

First off there's no ST tires in that size that uses 32 psi. The lowest is 50 psi.
All trailer rims are rated the same per size and all ST trailer tires have the same load ratings per size. Doesn't matter what brand.
14-5.5 rims are rated for 2200 lbs.
205/75/14 LRD are rated at 2040 lbs at 65 psi.
If you have newer style aluminum rims, that is you're not looking to put tires on a 20 year old TT then the above ratings would apply to you.

[93Cobra2771]

Agree with above - max sidewall PSI

[colliehauler]

As long as the Rims can handle the pressure won't hurt to run at higher psi. This will not increase your load carrying capacity because of axle ratings. The Rims should be stamped on the inside with max psi rating.

[afidel]

The only question is can the rims handle 65psi, hopefully whoever mounted them would have noticed if they couldn't but I'd double check and then air them up to Max cold.