Tires for 1987 34W, original aluminum rims... suggestions?

[KYAvion]

Paul-

I talked with Discount Tire. Of all the trailers they've done, they claim to never have seen a max tire pressure on the wheel.

I have to pull a tire off to make a brake adjustment. Do you recall where on the wheel you found the pressure data?

This would make me question whether they know what they are talking about. It’s not unheard of for the max rating to be stamped on the back or inside of the rim.

[KYAvion]

Given the tri-axle trailers came with Load Range C tires, consider that Load Range D will likely provide more than an adequate margin. With three Load Range E’s, something to look into is whether the ride will be significantly rougher? Perhaps not. However, if the PSI has to be dropped to soften the ride (which is NOT a great idea), then I think it would be better to go with Load Range D’s at max pressure.

[Razorback]

As far as valve stems, I prefer the bolt on metal valve stems.

They showed me the stems this morning.... looks like exactly what they will install.

[Razorback]

Given the tri-axle trailers came with Load Range C tires, consider that Load Range D will likely provide more than an adequate margin. With three Load Range E’s, something to look into is whether the ride will be significantly rougher? Perhaps not. However, if the PSI has to be dropped to soften the ride (which is NOT a great idea), then I think it would be better to go with Load Range D’s at max pressure.

Last night when I pulled off the first 3 wheels, under the grime on the inside of the wheel were the PSI markings I mentioned earlier.... 65psi for radials, 60psi for bias ply.

As for the load range E tires.... I think I will set them in the 60-65 psi range and see how that does.

[KYAvion]

I can understand your logic at reducing the PSI to 65, but consider you may be better off with Load Range D set at max PSI instead.

Below is cut and paste from an old thread when I had a relatively new tire come apart on my prior Airstream. The feedback I got was from someone who was apparently a tire engineer (not to be confused with a
tire salesman : ) )


With Michelins, run at MAX PSI or reference the air pressure chart? I see there may be a couple different schools of thought on this matter.

Google "Interply Shear RV Tire" to learn why running tire sidewall pressuer is better fo multi axle tires. Why worry about tread wear on a tire you will replace before it wears out?


Would Load Range E tires be better in the future in the case of a tire failure? Mentioned was that the other tire on the same side as the damaged tire may now be more likely to fail due to being overloaded when the tire failed. Would LRE tires be better so they could handle such a failure better, or would the ride be too harsh for this trailer since I gather they would need to be run at their max (80 psi?)?

Save the money and get a TPM system and avoid the failure in the first place.

[Razorback]

I sent an email to Roger (tireman9) describing my tire issue and my purchase... here is the text of that email:

"Hi, Roger. Thank you for all of the helpful information you provide to us!!


I have a question regarding tires I bought for our 1987 Avion travel trailer.

Details:

34' trailer, three axles

15" x 6" aluminum rims, says 6JJ and max. 65psi for radials.

Trailer originally came with H78x15 LRC tires. Trailer specs say 6850lbs empty, max weigh 9500 lbs. I have never weighed the trailer, but I would say we are light travelers compared to most. We don't bring a lot of "stuff" with us, ever. Never travel with full tanks on the trailer... maybe 20 gallons of water in that tank.

Had GY Marathons on it (ST225/75R15, LR D) when I bought it 5 years ago.

Replaced with same dimension Commodore brand ST225/75R15 LR D's shortly after purchase.

I pay attention to inflation pressures closely.... usually ran 60 psi (I think that was the stated max pressure on the sidewall, will verify)

Came home from a camping trip Sunday and was putting X-chocks on the road side and noticed a tread problem on the front tire. I am assuming it had a tread or belt issue, but it caused a bulge in the tread. Thanked God that we made it home without a catastrophic event, then....... off to my favorite shop to get some new tires.


I have bough a set of 6 Hi-Run ST225/75R15's, LR E, item #WD1231 (https://sutongctr.com/tires/jk42/). Sidewall says max pressure 80lbs, their table says max load 2830lbs. I will never have that much weight on them.

I hope I have not made a mistake here. My plan was to run these tires at 65psi....... do you think I'll be OK? Mainly thinking of interply shear. (I cannot find any load numbers for 65psi for these tires).


Thank you for your input."

Roger has joined us here!

[Razorback]

BTW, I retrieved the old tire from the shop this morning. There is a bulge/bubble on the inside of the tire under what I had noticed on the tread. I will try to get some decent pictures to post here.
The Commodore tire had a DOT of RYB4 0MAC 0214.
I did my best to post a complaint on the DOT site:
"Your Complaint Information is successfully submitted.
Your Confirmation number (ODI Number) is: 11129215 "

[Razorback]

Found a picture on Roger's blog (www.rvtiresafety.net) that is a good representation of what I saw with my tire, in this post http://www.rvtiresafety.net/2013/11/int ... abble.html:

[Tireman9]

Bolt-in metal valves are definitely a good move for any RV.
Standard low cost "snap-in" rubber valves are only rated for 65 psi when new and the older they get the lower pressure they can probably handle. I have a few blog posts with more background info on valves & valve cores.

RE Pressure.
Multi-axle trailers place unusual loading on tires. This force is called "Interply Shear" and can result in belt separations in radial tires. I have a number of posts on my blog if you want the background, including some research engineering reports, but the bottom line is
1. You should keep the actual scale load to no greater than 85% of the load capacity of your tires.
2. Increasing tire pressure can reduce the Interply Shear but not eliminate it. This is why I and others suggest running the pressure molded on the tire sidewall if possible.
3. Do a simple alignment check yourself by measuring the center to center on the outer end of your axles. The two measurements ( right and left side)need to be as identical as possible ( +/- 1/64" or less ) I have seen aftermarket kits that allow you to adjust the axle alignment your self with hand tools, jack and tape measure.
4. If your RV came OE with LR-D you can run LR-E tires and less than 80 psi but use the extra inflation capability to get the trie capacity high enough to give you that 85% figure. Similar with going from LR-C to LR-D.

[silverloaf]

Tireman9-

The toe and camber adjustment procedure and specs on our trailer are rather crude when compared to a car or truck.

Our trailer has 4 independent axles. They each pivot on a steel shank bolt within two brackets (2 axles/bracket) located in the center of the trailer. Steel shims are spaced between the bracket and each axle yoke to adjust the toe. Camber adjustments are made by moving the bolt and yoke up or down between three holes in the bracket.

The toe measurement is performed by creating a wood straight edge. It makes contact with the wheel (not tire) and extends just beyond the tire. Measurements are taken from the trailer frame to each end of the straight edge. The differnence is the toe setting.

The procedure says to set each tire statically to a positive toe of 1/8". The rolling resistance of the tire in motion wiil then convert the static to the desired "0" toe. Repositioning the shims changes the static toe in 1/8" increments.

All this being said, do tires perform best at 0 toe?

Thanks for joining the forum.