Tires - Making sure

funpilot · 11-15-2014, 06:40 AM

I should be getting my new trailer in about two weeks so am looking to immediately replace the Marathons with Maxxis and keep the Marathons as spares. Since I am getting perhaps the heaviest TM made today (3124KD) I have been persuaded by discussions here and elsewhere to get "E" rated. Here is a link to the tire I think I should get: Please comment.

http://www.discounttiredirect.com/di...25&ar=75&rd=15

I also want to get wheels for these tires. Anyone know the current bolt pattern for this trailer? Any suggestions on wheels?

I do remember to get the better valve stems.

funpilot · 11-15-2014, 06:46 AM

Just saw this Q&A on eTrailer:

Can a Load Range E Trailer Tire be Used in Place of a Load Range D Trailer Tire

Question:

I wanted to know if I can go from the 225/75R15D tire that I currently have on my trailer, to a 225/75R15E tire? Will my current wheel, be able to handle the increased tire pressure needed for the E load range rated tire? I've been reading about wheel ratings for tire pressure, and I'm not sure what my current wheel is rated for. I was just curious, if I were to have E load rating tires installed, if I would need to have different wheels to match the tire pressure rating for the new E load tires. The tire person I spoke with, said I could just run the same tire pressure of 65 psi as with the D load rating tires I have on there currently. The reason why I'm asking is, they have the E load rating tires in stock and my load on the trailer hasn't changed. They said the E load rating would just be a higher load rating if nothing more, especially when running the tire pressure at 65 psi. It would just handle the same load as my D load rated tire I have on. Is this correct? Just curious to know, so I'm not doing something that's wrong.

asked by: Martin

Expert Reply:

Different size and bolt pattern wheels that take the same tire size will have different psi ratings. If your existing wheels are rated for 65 psi then it is less likely that they would also be rated for 80 psi which is what an ST225/75-15 load range E tire requires.

Trailer tires should always be inflated to the maximum psi as indicated on the tire. The person you spoke with must not have known about the difference between trailer tires and passenger vehicle tires. Trailer tires are made with a thicker sidewall and if they are under inflated they would generate excessive heat and cause the tire to fail.

If you wanted to go to load range E I would also replace the wheels. We have 1 tire and wheel combo in this size, # AM32680, and it has a 6 on 5-1/2 inch bolt pattern. To give you an idea of where we are coming from our tire guru has over 30 years of experience in the tire industry.

Also keep in mind that going to a higher capacity tire does not increase the capacity of the trailer. I have included a link to our tire FAQ article for you.

RottieMom · 11-15-2014, 07:46 AM

Reading posts on this site certainly makes me aware of things that I hadn't considered before. I just went out to see what tires are on my TM. They're Marathon ST225/75R15 D. I bought the TM new this past summer from a dealer (even though it's a 2013). I don't know the year they were manufactured, but I hope they're only a couple of years old. I've only taken it on two trips and won't be taking it anywhere till Spring now. One thing I had a problem with the first time I took it out was when I checked the air pressure and saw I needed to add some. I got my air compressor out and started to add some air and had a heck of a time as the tire stem was wiggling all over the place. Later on, I found out from an RV maint and repair shop that the stems could be changed out to metal stems for just a few bucks. I plan to have that done this Spring when I get the TM out.

Padgett · 11-15-2014, 08:11 AM

Had a long post hit backspace and it all went away. In short the Load Range of a tire varies with the section width and the inflation pressure. Inflate a LRE tire to 65 psi and it will have the same load rating as a LRD tire for a 225x75 that would be 2540 lbs

If you want you could graph the pressure vs load and not be far off. 1875 lbs at 44 psi, 2150 at 50, 2540 at 65, and 2830 at 80.

In general a steel wheel is stronger than an aluminum one. Though I have not seen either fail without either impact or extreme overloading (e.g. autocrossing). For a 225 section I'd want a 7" rim though a 6" rim is probably OK.

With a 3124 odds are you have a 5k axle which comes standard with a 6 bolt wheel though I have been thinking about replacing my 3.5k axle with a 5k while keeping the 5 bolt hub so is not for sure and for certain.

Final things: in any trailer tire I would be looking for a nylon cap or overlay, essentially an extra belt to stabilise the tread and as with a new car tire, get it balanced - you probably will not feel an out of balance tire on a trailer from the TV and there is no shock absorber to dampen oscillations. One of mine took 3oz.

Below is a graph of load vs psi for a 225x75. As you can see it is pretty linear.

funpilot · 11-15-2014, 10:49 AM

Padgett, I hope you are correct on the 6 bolt wheel as they are the only ones I have found rated to take 80 pounds of air pressure. I will chase down someone at TM on Monday and verify

**ShrimpBurrito** · 11-15-2014, 03:42 PM

Quote:

Originally Posted by funpilot

Padgett, I hope you are correct on the 6 bolt wheel as they are the only ones I have found rated to take 80 pounds of air pressure. I will chase down someone at TM on Monday and verify

Speaking from experience, I don't think you want to travel with 80 psi. The trailer will get shaken to death and stuff will quickly start coming loose and falling apart. Several folks here, including myself, travel with lower pressure levels (~65 psi) in load range E tires.

Dave

**ShrimpBurrito** · 11-15-2014, 03:44 PM

Afterthought -- instead of replacing a brand new set of tires, why not simply ask the factory to install what you want to begin with? Seems silly to buy a new set of tires and then toss them, and I can't imagine them not being willing to accommodate such a request.

Dave

hillbillyhotel · 11-15-2014, 05:04 PM

+1 on that , I run at 65 psi,

funpilot · 11-15-2014, 08:05 PM

Quote:

Originally Posted by ShrimpBurrito

Speaking from experience, I don't think you want to travel with 80 psi. The trailer will get shaken to death and stuff will quickly start coming loose and falling apart. Several folks here, including myself, travel with lower pressure levels (~65 psi) in load range E tires.

Dave

Good advice. I will also ask them about the tires.

Padgett · 11-15-2014, 10:19 PM

BTW I doubt that any modern trailer tire in our sizes is actually 10 ply, Rather in days before radials and such the standard bias ply tire had 4 plies laid at 45 degrees (the bias) to each other.

Then we goth something called 2 ply/4 ply rating (PR) that weren't even safe in the driveway (B.N.). Then came the bias-belted briefly followed by the radials that Michelin had been pusing since the 60s).

So before there were Load Ranges, we had Ply Ratings (PR) and basically a 4 PR was a standard tire, 6 PR a LRC, 8PR LRD, and 10 PR LRE.

What I am saying is that I would be surprised if a MAXXIS LRE atually had 10 plies, more likely 2 or3 polyester, two steel, and one nylon (if it has a cap). Easy to find out, it is molded in the side of the tire.

Also the plies in the sidewall are often less to give more compliance (flex) to the tire. This is why a sidewall puncture can usually not be repaired (though I have heard of some people adding a tube), the sidewall is too weak to support a fix.

Below is from a LRD.