Forum Discussion

shakyjay's avatar
shakyjay
Explorer II
May 12, 2013

Another Tire Question

Time for new tires. Currently have ST205/75/15C's. They are the originals and up til now have been fine however age is taking it's toll and sidewalls are cracking. Stopped at America's Tire. Seems they now are not stocking the Towmasters which was one of the tires I was considering. Instead they have gone back to stocking the Carlisles that supposedly have been redesigned. I have done some research and it appears the new RH does have some improvements. After much discussion with the salesman who actually said he is running the Carlisles on his 13,500 lb. fifth wheel. He recommended that if I have the clearance to go with a Carlisle ST225/75/15 E rated tire. Supposedly it should only require about an 1.25 inches more of clearance. So my options are just replace with original size and range in a ST205 or what my original intent was to go ST205 in a D range or go up to the ST225 in load range E. Price between the three is really not that much difference D range $50 more than C and ST225 $80 more than C. The other option I am considering is to have him order the Maxxis. Price for them in ST250/75/15C is about $100 more than the same Carlisle. He absolutely did not recommend Marathons and said he could order the Towmasters but really did not recommend them either.

So after all that I am simply looking for some input to help me decide which option would be the best. I do not tow full time. Actually now days the trailer sits more than it moves. What travels we do use it for are generally no more than a couple of hundred miles one way. Occasionally we may go a little further. I do not run heavy but would like a little cushion.
  • brulaz's avatar
    brulaz
    Explorer
    May 12, 2013
    Your trailer must be about 8000# GVWR.
    For that I would want, as a bare minimum, a tire rated at 2000# each. (The tongue weight would provide some cushion)

    The ST205/75R15C is only rated to 1820#, so I wouldn't go that route.

    A ST225/75R15D is rated at 2540#. Much better.

    As for Carlisles, maybe they are getting better, but I still don't trust them. I would order in Maxxis ST225/75R15D. They will be more expensive though ...

    If you really like Roadmaster, you could order them over the internet and have the local shop put them on. But again I'd go with ST225/75R15D.
  • LarryJM's avatar
    LarryJM
    Explorer II
    May 12, 2013
    I agree with the 2K per tire and here are the load limits for 225 sized 15" ST tires

    "C" - 2150
    "D" - 2540
    "E" - 2830

    Issue is if your TT came with "C" then the rims might only be rated for 50# so "D" (65psi) and "E" (80psi) would/should need new rims as well. Both the C and D would be O.K., but IMO the E is overkill. Also an ST205R75x15(D) at 2150 would also be good. My choice would be the "D" at 2540 if your rims will take the PSI.

    Larry
  • JIMNLIN's avatar
    JIMNLIN
    Explorer III
    May 12, 2013
    Agree with Larry. A trailer unlike the tow vehicle can have too much tire. The Rockwood is a ultra lite trailer and all show a 6k-7k GVWRs.

    You didn't tell us what the trailers GVWR was or axle GAWRs but looking at '13 Rockwood web shows the biggest at a 7800 GVWR with a 1380 CCC figures about 1600 lbs per tire. Now add 15 percent for a nice capacity reserves and the the 205/75-15 C at 1820 lb work out fine.
    Higher pressure 65 psi tires require higher 65 psi pressure rated wheels. You want to run the ST tire at its max pressures so the wheel will need to be be rated to use 65 psi. Some 15" wheels are rated to 50 or 65 or 75 and 80 psi.

    No more than your trailer is on the road I would go with the 205/75-15 C at 50 psi. Brand is your choice as IMO a ST tire is still a ST tire and all brands have the same issues. Even the Maxxis ST8008 although they seem very popular at this time.

    Or the new and improved Carlisle RH may actually be improved.
  • LakeN's avatar
    LakeN
    Explorer
    May 12, 2013
    Ran a set of Maxxis on a camper we recently traded. Very pleased with performance. They never ran hot and seem to be the best tire at this time. They may cost more but a cheap tire blowout can cause TT damage which in the end could be more costly. We plan to put new Maxxis on new camper before too long.
  • skipnchar's avatar
    skipnchar
    Explorer
    May 12, 2013
    Think Maxxis. Never knew ANY Chinese made tire that could match them.
  • Gdetrailer's avatar
    Gdetrailer
    Explorer III
    May 12, 2013
    I personally feel that folks put way to much thought into the name on the tire. 99.9% of the tires are made by the same manufacturers onshore and off shore.

    Basically they just change the MOLDS which have the manufacturer name to be sold in it.

    I just replaced my Carlisles which had a manufacturer date of 7yrs (I had them for 6 yrs). The reason as to why I replaced them? Bad VALVE stems!

    Thats right, I had one valve stem over winter BROKE OFF.

    I decided since one stem broke the others would follow. Since I was needing to replace the stems it made sense to put new rubber on at the same time.

    A search of the Internet revealed that there was a bad batch of valve stems sold which lined up with the time frame I had the new tires mounted.

    There is a good chance that there is STILL bad valve stems being installed yet TODAY since there was millions of stems manufactured before the recall and many shops may have never seen the recall.

    Chances are many people have had a bad valve stem and blamed the TIRE MANUFACTURER for the tire blowing out.

    Simply put if the valve stem breaks it is the same result as a supposed "defective" tire, basically shredding the tire and trailer. The problem is the process of the tire shredding damages any evidence of the broken valve stem. Then EVERYONE on the forum jumps to conclusions and automatically blames the maker of the tire.
  • shakyjay's avatar
    shakyjay
    Explorer II
    May 12, 2013
    To clarify some of the questions the trailer has gvwr of 7980 max I run it about 7600. Tongue weight is about 1100. Don't really want to change rims as I can't see justifying the expense for what little we are running at this time. The tires on it currently are the originals from when it was purchased in 2006 and have never given any problems, even though they are Chinese made. One of them has developed a slow leak and sidewalls are beginning to crack on all of them. I do store it at my house and typically check pressure every couple of weeks. I always run my tires at max pressure on the trailer.

    My original thought was to go to a D rated tire seeing as to how there is really not much of a price differential. Salesman at tire store suggested the 225 E rated which sounded a bit like overkill to me. I think he is going off his own experience with a fifth wheel toy hauler that runs a lot heavier. In this area that is mostly what he sees and most of them run overloaded.

    So I guess that really just leaves me to determine if I just go with an exact replacement which is a C rated tire or jump it up to the D rated.

    Thanks for all your input it is really very helpful.
  • Chuck_Gail's avatar
    Chuck_Gail
    Explorer
    May 12, 2013
    Several points. First, as said, what are your RIMS rated for? Rating usually stamped on rear, or in valley UNDER the tire. Putting LR-D on a LR-C rim is a THIRTY PERCENT OVERLOAD. Not what I call safe. Obviously LR-E is an even worse overload.

    Second what is your current rim WIDTH? Most ST205/75R15's I've seen are mounted on 5 or 5.5" rim widths. Most ST225/75R15's seem to require a 6" minimum rim width. Again, be careful what you do.
  • Lowsuv's avatar
    Lowsuv
    Explorer
    May 12, 2013
    regarding the ability of the steel wheels being able to take 80 psi that has been addressed repeatedly on this forum .
    there are a bunch of misinformed posters who believe that these wheels will not allow 80 psi .
    that myth has been debunked at length by the most knowledgable tire guys on this forum such as capri racer , fast eagle , and others .
    the original steel wheels will take 80 psi with ease .
    regarding upgrading your tires it is more important to increase the load rating of your tire no matter which way you do it .
    Load Range and tire size are far more important than brand .
    So if you gan go from a "C " rated into a "D" or an "E" that is a good way to go.
    If you can go to a 215 or 225 section width over your stock 205 that is another way to go .
    the important number assuming you are only considering ST tires is the weight capacity in pounds your replacement tire is .
    there are plenty of choices in 225/75 R 15 in load range C and in load range D .
    in practical experience the advantage of a 225 over a 205 outweighs any issues with rim width .
    the best solution I have seen in 15 inch tires is the Continental Vanco 2 tire.

    http://www.tirerack.com/tires/tires.jsp?tireMake=Continental&tireModel=Vanco+2&sidewall=Blackwall&partnum=27R5V2&tab=Specs
    size 225/70R15 C has a load rating of 2470 pounds on an LT tire scale. This is also a tire that is rated for 99 mph unlike an ST tire at 65 mph rating .
    it is also available in a 215 section width , also with high load ratings.
  • shakyjay's avatar
    shakyjay
    Explorer II
    May 12, 2013
    Chuck I had not thought about the rim width. You are right they are only 5". Looks like that could be a limiting factor. The rims do not have a visible weight or psi rating anywhere on them. If it is there it must be stamped on the inside which really does not help as that means I won't know until they take the tire off the rim. I don't think there should be a problem going from C to D or which is going from 50 to 65 psi. I can see where going to 80 psi with and E rating could be an issue.

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