New Tires

[Sonny]

Just thought I would pass along some useful info. I recently took the cover off the spare tire on my Scamp 13 and found a large bulge under the tread, from a separated ply or belt. I shopped around for a replacement ST175/80R13, and found prices ranging from 70 to 110. I called Costco and got it for $59, including mounting and balance. It's a Towmaster, which I have been told is made by Michelin. They told me that they just recently started carrying trailer tires. I know who I will call first next time!

Anybody out there know what is different about trailer tires?

[Chris B]

There's been alot of discussion about tires on one of the Casita websites. It seems that Goodyear Marathon tires are failing, in some cases. I know that the tread on mine has worn differently than car tires. This was posted by one of the forum members. It's an easy read with good information.
http://www.discounttire.com/dtcs/infoTrail...ghQK30FM0Hj9ZzN

[Brian B-P]

..It's a Towmaster, which I have been told is made by Michelin...

Towmaster is a brand from Greenball. Their Company History page explains their sources, but basically they are an importer of tires from cheap sources. I would be surprised if any Michelin plant was the cheapest source for these guys, but I suppose it could be true. The tire coding experts among us may be able to explain how to read the cryptic codes moulded into the tire sidewall, which might list who really makes the tires.

[Brian B-P]

Anybody out there know what is different about trailer tires?

There has been a lot of discussion of this here in FiberglassRV, too. The Search tool can find the topics, but you can't search on very short keyword, such as the two-letter "ST", and "tire" might be a little to general... so I would try "Marathon", since just about every tire topic eventually mentions the Goodyear Marathon.

[Pete Dumbleton]

You might want to go back to Costco and ascertain that they know that trailer wheels require a special adapter on the balancing equipment because they are LUG-centric and the hub hole is just stamped and may not be the actual balance center of the wheel. Most US automotive wheel are HUB-centric.

You can generally tell that a wheel is lug-centric if the center hole is not in actual contact with the hub or hub-ring.

[Chester Taje]

You might want to go back to Costco and ascertain that they know that trailer wheels require a special adapter on the balancing equipment because they are LUG-centric and the hub hole is just stamped and may not be the actual balance center of the wheel. Most US automotive wheel are HUB-centric.

You can generally tell that a wheel is lug-centric if the center hole is not in actual contact with the hub or hub-ring.

Now this is real interesting.

[jim munson]

Now this is real interesting.

I recently had a huge blowout on my 13 footer. Bad damage on the fiberglass and the rim was ripped off the hub lost in the ditch.
I'm not sure why what failed-no way to tell. Loose lug nuts or tire failure?
What I know for sure is the tire was marked "P" for passenger!
Never knew that. I changed to 8ply Light Truck tires. Could not find any marked LT but the salesman said these are the best for heavy sidewall wear.

[Pete Dumbleton]

Chester, do a search of the group on "centric" and you will find some interesting info. Seems that some of the larger Toyota truck wheels, esp the after-market 4WD ones, are also lug-centric and the Toyota dealers weren't balancing them properly (taking mildly out of balance wheels and making them worse...).

Actually, according to some recent info posted to Yahoo Scampers, ST tires are indeed better for trailer use (more UV protection and interior belts and steel) than LT, which in turn are better than P-radials. Some folks have good luck with Ps, and probably less rolling resistance becasue of the less stiff sidewalls, but most RV groups recommend against them, as does my personal experience with them on my Jayco 16', because of their tendency to allow sway.

[Brian B-P]

I changed to 8ply Light Truck tires. Could not find any marked LT...

Light truck tires are really hard to find in the size of a stock small travel trailer tire. They might be a commercial tire. What size did you get, Jim?

Also, the "ply" numbers don't really mean construction plies anymore. They're probably load range D tires, with a 65 psi maximum inflation pressure; what do they say they are?

[Alf S.]

Hi: Getting ready to "Tug To Emily" for the "Retro Rally" I buffed my Baby Moons only to discover sidewall cracks in my... Prev. Own's. description "New Tires Now I thought was a good time to go Radial...3 new Tires The only radials my trusted R.V.Dealer can supply are Goodyear Marathons and I feel insecure towing with cracked Carlisle's??? Alf S. North shore of Lake Erie p.s. 2 New bias Carlisles @ $95.00ea or 3 radial Marathons @ $78.00ea.

[Joe Z]

Hi Alf...
While there are many good tires out there I have been reading about "Kuhmo Radial 857" tires a real lot lately and i have not heard one negative thought on these tires... do a search in the forums on this tire...........
I have the "goodyear marathons" at the present and will be switching over to the "Kuhmo's" as they have a heavier ply and a higher speed rating and if you purchase these be sure to get the metal valve stems for the increased tire pressure that they use.... also be sure that your rims can carry the extra load rating tires.
Joe

Link to "Kuhmo radial 857"
http://www.tirerack.com/tires/Sizes.jsp?ma...odel=Radial+857

[Steve L.]

(Propeller Beanie turns on...)

A few minutes with the Tire & Rim Assn handbook yields the following capacities:

P205/75R15SL (standard load): 1452 pounds at 35 psi (when used on a trailer)
P205/75R15 XL (extra load): 1553 pounds at 38 psi (when used on a trailer)
LT205/75R15C: 1655 pounds at 50 psi
ST205/75R15C: 1820 pounds at 50 psi

I chose that size because it's common across all the tables and they are all dimensionally basically equal.

Note that the P tires carry about 41 pounds of load for every 1 psi of inflation. The LT (33) and ST (36) carry less load per psi but more load ultimately because of the higher allowed inflation. (A side benefit is that properly loaded and inflated ST and LT tires deflect less and put their sidewalls in less danger from road hazards.)

Air carries the load. The tire carcass and steel belts basically holds the air inside. The tire companies have formulas (basically throw backs to the old steam boiler formulas) that determine how much material to put in the belts and plies based on air pressure and maximum load. Then, they will add to the belt strength as required to accommodate the expected usage of the tire.

Of the four tire sizes shown, the ST tire would start from the strongest position. The LT tire would calculate out to have slightly less material, but then they would add belt strength to account for the rougher roads a light truck is likely to see.

[Brian B-P]

...2 New bias Carlisles @ $95.00ea or 3 radial Marathons @ $78.00ea.

The price difference is a little surprising to me, given that the Goodyear brand is not commonly a cut-price offering and there's nothing special about Carlisle. Are they really comparable; that is, are both tires the same load rating?

[Brian B-P]

...I have the "goodyear marathons" at the present and will be switching over to the "Kuhmo's" as they have a heavier ply and a higher speed rating...

The Kuhmos are a commercial tires, not ST (one of the errors in this Tire Rack page); in my view there's absolutely nothing wrong with that, and it may help explain the higher speed rating.

The "heavier ply" presumably means a higher ply rating - that is just another way of saying that the Kuhmos are are load range D tires; 14" Marathons are only available up to load range C. If the Load Range C tires have appropriate capacity, is there really a point to going to heavier "D" tires? It's not a quality rating...

The higher speed rating does seem to me like a factor worthy of consideration.

[jim munson]

Here's the whole scoop, Brian on my 13 footer" tires.
Capitol Korea $59.00
185 R14
DOT 8erk
65psi
LT load range D
Maybe these won't blow out!

[Brian B-P]

Thanks Jim.

So they are a load range D tire, with the usual inflation pressure for that load range. The surprising part, to me, is that there is a tire as small as 185R14 of the LT type.

Could this be the Jupiter/Capital SV-820? If so, it appears to be a commercial tire. The Michelin Agilis which I mentioned in an earlier topic appears immediately above it on the same page. This seems like quite a reasonable choice, although for my 17' Boler I want a larger size (even the stock is 205/75-14).

Another source (Roadhaus) lists it as a LT tire as well, and notes that it is "made by Kelly-Springfield". This is a VW camper site; light commercial Euro vans use tires about the size of our larger trailers, and need load capacities higher than is common in North America for that size, so VW van fans are often concerned with finding suitable tires, and find these commercial products (as well as small LT sizes).

[Alf S.]

The price difference is a little surprising to me, given that the Goodyear brand is not commonly a cut-price offering and there's nothing special about Carlisle. Are they really comparable; that is, are both tires the same load rating?

Hi: Brian... The price for the Carlisle's( bias or radial) was at OK Tire the price for the Marathon's(radial) was from our local R.V. Dealer Maybe he likes me as I spend a good deal of $$$'s there!!! I said to him that this might be a good time to repack the wheel berings and he said he would do them for $30.00 Alf S. North shore of Lake Erie

[bobinyelm]

The Kuhmos are a commercial tires, not ST (one of the errors in this Tire Rack page); in my view there's absolutely nothing wrong with that, and it may help explain the higher speed rating.

The "heavier ply" presumably means a higher ply rating - that is just another way of saying that the Kuhmos are are load range D tires; 14" Marathons are only available up to load range C. [b]If the Load Range C tires have appropriate capacity, is there really a point to going to heavier "D" tires? It's not a quality rating...

The higher speed rating does seem to me like a factor worthy of consideration.

The Casita 17ft trailers have been having NUMEROUS tire failures (bulges, tread separation, etc.) with Marathon Load Range C tires (go over to either the Casita Club Forum or the Casita Travel Trailer Forum and do some searches).

MANY of us have gone to the Kumho 857 Radial Tires. They offer 20% more weight capacity per tire (2240# vs. 1850#) beside offering 8 ply rating and a 99mph speed rating, all for LESS than the cost of Marathon "Load C" STs in the same size.

Not one complaint or failure by anyone running them yet.

Bob

[Brian B-P]

I suspect that the condition "If the Load Range C tires have appropriate capacity" isn't really being met in some cases. With moderate underinflation, unbalanced loading, and highway speeds, perhaps too much is being asked of the load range C tire? A higher load range is one solution; larger tires might be another. I'm not trying to re-open the "failing Marathons" debate... it is for trailers not pushing the limits, that I wonder about the higher load range (also described as a higher ply rating).

[MikeC]

The Casita 17ft trailers have been having NUMEROUS tire failures (bulges, tread separation, etc.) with Marathon Load Range C tires (go over to either the Casita Club Forum or the Casita Travel Trailer Forum and do some searches).

MANY of us have gone to the Kumho 857 Radial Tires. They offer 20% more weight capacity per tire (2240# vs. 1850#) beside offering 8 ply rating and a 99mph speed rating, all for LESS than the cost of Marathon "Load C" STs in the same size.

Not one complaint or failure by anyone running them yet.

Bob

I just purchased a pair of the Kumho's too for my 16 SD, but haven't used them enough to make any judgement about them. When I asked the dealer where I purchased them if he had balanced them using the lug-centric adapter, he kind of looked at me with a blank stare. I'll be going elsewhere for a re-balance.

What the dealer told me, however, is that given the traveling weight of my SD (I estimate between 2600-2700 lbs. loaded,) I should be able to run them at 50 PSI (max is 65 PSI.) Anyone have any thoughts on that? It sounds reasonable, but given his response regarding the balancing of the tires, I don't have the warm and fuzzys about the dealer's PSI advice .