Need tires - upgrade to 16"?

DageonYar · 10-04-2010, 08:27 AM

I could have sworn I saw a sticky here somewhere on this subject, but my searches came up empty. I'm going to need 4 new tires for my FW, which currently has 6lug 15" wheels on it. However, searching around, there are very few choices in a D or E load range 15" tire. So I was wondering if I move up to a 16" rim, can I then look at putting on a E range truck tire in approximately the same profile? Do I absolutely 'need' to have a tire specifically made for a trailer? With all the threads recently discussing blow-outs, I really want to make the proper choice on this before our trip out to PEI next spring.

TIA.

**Herk7769** · 10-04-2010, 08:31 AM

I would be very hesitant with this mod.

jackhartjr · 10-04-2010, 08:57 AM

I went with a 10-ply Maxis, not sure what the load rating was, I just know it was a lot more than the weight called for. You want to stay with trailer tires, not truck tires. Good luck.

**Herk7769** · 10-04-2010, 09:04 AM

I replaced my tires with Goodyear Marathons. They are ST tires and up gunned them to D range from C. Remember your rims must be rated for the higher pressures if you inflate the tires to their maximum.

turbopuppy · 10-04-2010, 10:19 AM

First off. Going plus will raise the trailer. Mileage may change. But RV people wouldn't be RV people if we cared too much about the overhead

I also thought about doing this once and decided not to - just because it would be aerodynamically higher (higher profile), and harder to reach the first step. The first step was already tricky for the kids and didn't want to challenge them more. Also, you might need an adjustment at your shank to level the tow after the switch. But that would be easy to fix.

As for the benefit: well you get .5" more clearance. Hmmm. I like the "look" though. Especially with nice aluminum rims, chrome lugs, trim ring. yup. You wll increase your safety margin and never come close to overloading the wheels (but limit is unchanged for axles, spindle, brakes, studs, etc)- tire life may increase and tire temps will not be any problem you'll see. Unless you're speeding.

As for the tire discussion: You stated you were shopping for D or E rated 15" tires - trailer tires already have appropriate sidewall configuration for trailer use. Max load on wheels smaller than 16 (16.5??) CANT use higher rated tires because the wheel would fail. So why manufacture a tire that is rated higher than a wheel could carry anyway. Anthing heavier would be on larger assemblies, right? The wheel itself couldn't take it. I know you don't mean to overload your current 15's, I was just discussing why one cant find E tires for 14" rims. None being manufactured. I am surprised you found ANY E rated tires for 15" wheels. There are 16" (16.5"?) wheels - and tires to go with them. I would confine my shopping decisions to those, personally.

"But, I am not a real doctor. I have a degree in science."

Please reply later any share what you worked out.

NWJeeper · 10-04-2010, 11:35 AM

Quote:

Originally Posted by turbopuppy

First off. Going plus will raise the trailer. Mileage may change. But RV people wouldn't be RV people if we cared too much about the overhead

Not true. Wheel size has nothing to do with the tire rolling diameter. 15" or 16" rim makes no difference, you simply buy the right size tire you need to maintain the correct rolling diameter. What changes is the height of the sidewall.

Mileage would also not change as it is a trailer not a car. When changing the outter diameter of a tire on a car it in effect changes the differential gear ratio that is why mileage changes. On a trailer it would make no difference.

**Herk7769** · 10-04-2010, 01:34 PM

There are several other items in your post that are not correct as well.

There are many threads here about trailer tire's; pressures; and manufacturer guidlines that contradict your statements.

I attached excellent sources for tire data:

turbopuppy · 10-04-2010, 10:49 PM

OK then. It was just a guess, I guess. Thanks alot, "super moderator"

DageonYar · 10-05-2010, 06:21 AM

Well, I'm still in 'research mode' for the time being. Not in too much of a rush. Don't need the tires until spring now. I have been poking around the local RV dealership and did notice many of the new 5'ers are sitting on LTs. Makes me wonder if the builders are putting LTs on now, it should be fine no? I have found very few 15" STs available, and they all appear to be made in China... probably better to run on bicycle tires in that case

donn · 10-05-2010, 07:51 AM

LT tires are very common on large fivers. Easier to find, more reliable, more choices. Other than the added cost for wheels there is really no negatives. Do a web search, there are several companies that have package at attractive prices. Bottom line, no more junk ST tires to worry about.

bsmall · 10-05-2010, 08:50 AM

My 2010 Wildcat 28RKBS came with the 16" ST's on the ground and the spare was an LT tire. I have not crawled under the trailer to read the side wall for weight information to compare with the ST's that are on the ground....

**Herk7769** · 10-05-2010, 12:38 PM

From an Airstream forum Post:

"Yes, there is a definite difference between Cooper LT and ST tires.
However, it is not a "safety" difference as long as the load rating is correct for your trailer's gross weight when towed. Both ST and LT tires can be safely used for trailers. The difference in construction is this: Cooper ST tires are basically a tire that combines passenger car tire construction techniques, with heavy duty truck tire fabric and cord materials. This results in an ST tire having a high LT type load rating with the lower air pressure requirements and soft, shock absorbing sidewalls of a passenger tire. There is also extra UV inhibitors and oils added to the rubber to help in storage. This is much easier on the suspension and other components of the trailer on bumpy roads than the stiff sidewalls and higher air pressure of the LT tires. As far as tire safety is concerned, he stated that is up to the owner and how he maintains the tires, keeping the proper air pressure in the tires, and choosing the correct load rating. He stated LT tires have an advantage because of the larger choice of tread patterns and number of sizes available to choose from to suit the conditions you are towing in, such as snow, unimproved roads, etc. He also stated that it is imperative to not allow the trailer to rest on the tires in the same spot for months at a time in the off-season. This causes the fabric cords in the tire to take on a flat "set" which can then cause some of them to actually break apart when you next take the trailer out on the highway. This can cause complete tire failure. He stated the best thing to do is to store the trailer on jacks with the tires in the air, or removed completely. This last information was of concern to me since I only have "stabilizing" jacks and cannot lift the trailer enough to take the load off the tires without serious effort. At any rate, that is what Cooper Tires has to say on this subject."

Don't shoot the messenger

HobbyTalk · 10-08-2010, 07:02 PM

Maxxis makes 15" ST tires in C, D and E load ranges. They are available from Discount Tire (if not listed you can ask them to order them for you). They are made in Thailand and reports have been very good. Just make sure your rims can take the extra air pressure of the higher rated tires. The max. air pressure should be stamped on the inside of the rim.

Dave_Monica · 10-08-2010, 07:54 PM

Out of curosity, what are the current tire load rating and what are your camper's axle ratings. I'm assuming that you're looking to increase the safety margin...how much safety margin to you have now with 'D' rated ST tires.

Aslo, I wouldn't discount the use of LT tires...switching to them seems to be the trend lately.

Dave

DageonYar · 10-09-2010, 11:01 AM

Currently have 4 225/75/15 Titan ST load rating D. Not sure of the axle ratings. Would that be marked on the axle somewhere? The plate on the side says GVWR 11575 and GAWR 5250 lbs.

donn · 10-09-2010, 12:12 PM

Quote:

Originally Posted by herk7769

I would be very hesitant with this mod.

WHY?
Changing over to 16 inch tire and wheel packages is very common and relatively easy to do. All one needs do is contact someone like Trailer Tire and wheel company and ask the question. Be prepared with your original size and they can fit you with the correct package for a simple bolt on installation.
I guess if you want to be stuck with a nearly extinct tire size and limited to only a few choices most made in China, then stick with what you have.
Personally 16 inch LT tires can be found in almost any town in N America that will do the job in a pinch. Same cannot be said for 15 inch St tires.

donn · 10-09-2010, 12:17 PM

Quote:

Originally Posted by herk7769

From an Airstream forum Post:

"Yes, there is a definite difference between Cooper LT and ST tires.
However, it is not a "safety" difference as long as the load rating is correct for your trailer's gross weight when towed. Both ST and LT tires can be safely used for trailers. The difference in construction is this: Cooper ST tires are basically a tire that combines passenger car tire construction techniques, with heavy duty truck tire fabric and cord materials. This results in an ST tire having a high LT type load rating with the lower air pressure requirements and soft, shock absorbing sidewalls of a passenger tire. There is also extra UV inhibitors and oils added to the rubber to help in storage. This is much easier on the suspension and other components of the trailer on bumpy roads than the stiff sidewalls and higher air pressure of the LT tires. As far as tire safety is concerned, he stated that is up to the owner and how he maintains the tires, keeping the proper air pressure in the tires, and choosing the correct load rating. He stated LT tires have an advantage because of the larger choice of tread patterns and number of sizes available to choose from to suit the conditions you are towing in, such as snow, unimproved roads, etc. He also stated that it is imperative to not allow the trailer to rest on the tires in the same spot for months at a time in the off-season. This causes the fabric cords in the tire to take on a flat "set" which can then cause some of them to actually break apart when you next take the trailer out on the highway. This can cause complete tire failure. He stated the best thing to do is to store the trailer on jacks with the tires in the air, or removed completely. This last information was of concern to me since I only have "stabilizing" jacks and cannot lift the trailer enough to take the load off the tires without serious effort. At any rate, that is what Cooper Tires has to say on this subject."

Don't shoot the messenger

UHHH where did you get this bit of misinformation from?
ST tires are designed as a trailer only tire. Have a speed rating of 65MPH and are generally bias ply tires. Which by the way became obsolete about 30 years ago for all except trailers. They claim to be built with a stiffer side wall to accommodate the turning forces placed on them. Baloney! Radial ply tires are far superior in every respect and with the proper match will have the same or higher load ratings at a lower cost. Remember your business class on the law of supply and demand?

donn · 10-09-2010, 12:20 PM

Quote:

Originally Posted by DageonYar

Currently have 4 225/75/15 Titan ST load rating D. Not sure of the axle ratings. Would that be marked on the axle somewhere? The plate on the side says GVWR 11575 and GAWR 5250 lbs.

Yes, the axle ratings are marked on a metal tag that is affixed to each axle. Crawl under and look. You will also find the same information on a metal tag that is on the left front corner of your trailer. This tag will give you axle ratings, tire ratings and the vehicles GVWR plus the serial number.

HobbyTalk · 10-11-2010, 06:46 AM

My guess is he is going to have 5K lb axles. So the load rating of each tire will need to be 2500 lbs or more. Maxxis 225/75R15 D rated (8 ply) tires are rated 2540 lbs. That tire has a dia. of 28.3"

The smallest Michelin XPS Rib (LT tire) is a 215/85R16 with a rating of 2680 lbs each but the dia. is 30.4". The OP needs to make sure that they would have clearance for the larger sized tire.

Also to consider is that the XPS Rib will cost about twice (plus the cost of new rims) as much as the Maxxis. The really funny thing is as I was looking up prices at Discount Tire is that they carry (or can get) the Maxxis tire but the Michelin XPS Rib is not available in our area.

RhoZeta · 10-16-2010, 03:24 PM

Quote:

Originally Posted by donn

WHY?
Changing over to 16 inch tire and wheel packages is very common and relatively easy to do. All one needs do is contact someone like Trailer Tire and wheel company and ask the question. Be prepared with your original size and they can fit you with the correct package for a simple bolt on installation.
I guess if you want to be stuck with a nearly extinct tire size and limited to only a few choices most made in China, then stick with what you have.
Personally 16 inch LT tires can be found in almost any town in N America that will do the job in a pinch. Same cannot be said for 15 inch St tires.

While I do agree that 16" tires are the way to go, I think your assertion that 15" tires are nearly extinct and hard to find is a bit overly dramatic and a lot of hot air... you almost sound like you work for some political action committee to promote the use of 16" tires thru some sort of lobbying effort....

If you go to any wally world or Sams club, (in N. America and well beyond) you will find Goodyear Marathons in 14", 15" and 16" If you go to any Discount Tire in N. America they also sell the Marathons in all sizes, as does NTB or Tire Kingdom depending on where you are. Both Firestone and Goodyear service centers carry their own brand of trailer tires in 15" and others as well.

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