15" rims on a 17'

[fbaggins]

17b 2008

has anyone tried this?
what size tires?
what offset?

is there any real advantage?

[J Mac]

Originally Posted by fbaggins

17b 2008

has anyone tried this?
what size tires?
what offset?

is there any real advantage?

All tires, including trailer tires, have a best before date. if your tires are reaching that date, and you're considering aluminum rims, why not up sizing to 15" tire and aluminum rims from your existing 14" tire and rims. Don't forget your spare.
To answer your question, not much if any advantage.

[thoer]

Originally Posted by fbaggins

17b 2008

has anyone tried this?
what size tires?
what offset?

is there any real advantage?

I put 15" aluminum rims and tires on our 2010 17B. I used ST205/75R15 D rated CARLISLE RADIAL TRAIL RH. I like the idea of the 15" D rated being far below their maximum rated capacity given the weights of our 17. They are at max weight capacity at 65 psi, but even at 50 they have a bit more capacity than the C rated. I usually run them at about 55 psi.

I believe our trailer wheels are 0 offset.

[gbaglo]

I got 15" rims and the high-lift axle as original. Replaced tires recently with same tires as Thoer. Lots of room.

[Brian B-P]

Originally Posted by fbaggins

what size tires?

The original 14" size was presumably ST205/75R14 (although there have been changes over the years). The current Escape size, and a sensible choice but not the only one, is ST205/75R15.

This would mean the same tire width, the same sidewall height, and simply one inch larger overall diameter.

Originally Posted by fbaggins

what offset?

Conventional trailer running gear is designed to have zero or very small positive offset, and the recent trend has been to zero. Unless you go significantly wider with the new tires - and the likely choice is the same width - there's no reason to change to an uncommon offset.

Originally Posted by fbaggins

is there any real advantage?

The one-inch increase in overall diameter means rough a half-inch increase in the height of the axle above the ground, so you gain that in ground clearance (and the coupler will sit a half inch higher as well).
The slightly larger diameter increases the capacity of the tire, so it can be run at a slightly lower pressure, or with a slightly greater margin of capacity at the same pressure. The wear and heat buildup for the load would be slightly lower. These will all be small changes.

In high-performance cars and serious working trucks an increase in wheel diameter allows larger brakes to fit, but that doesn't matter at all in this case, because even the 14 inch wheel has lots of room for the 10-inch brakes.

[msweet]

Originally Posted by fbaggins

17b 2008
has anyone tried this?
what size tires?

I just had ETI replace the original ST205/75R14 tires and rims on our 2009 17B with ST205/75R15 tires and white steel rims yesterday. I went with the 15's for the slower rotational speeds to reduce wear and heat buildup on the tires and bearings. The decrease is minimal at 3.7% but everything helps!

The cost was $133 per tire plus $6 per centre cap plus half an hour labour to install - all in was $513.50. I had tried a few tire stores and they were asking over $100 per tire plus $50 a rim plus mounting, balancing, installation, environmental fees, disposal fees, etc.

I hadn't considered that the larger tires would affect the spare tire mounting bracket. There is just enough room to get the tire on but the tire cover doesn't fit. I loosened the bolts, raised the bracket, put the cover on and then tightened it back up. I will need to make a 1/2" spacer plate to make it more user friendly in the future. Until then the tire changing toolkit must include two 1/2" wrenches so I can loosen the bracket first! I guess you could call that a theft deterrent?!

[Brian B-P]

Originally Posted by thoer

I put 15" aluminum rims and tires on our 2010 17B. I used ST205/75R15 D rated CARLISLE RADIAL TRAIL RH. I like the idea of the 15" D rated being far below their maximum rated capacity given the weights of our 17. They are at max weight capacity at 65 psi, but even at 50 they have a bit more capacity than the C rated.

"ST" tires are made to the Special Trailer standards of the Tire & Rim Association, so tires of the same size and load range from all manufacturers have the same capacity. In the TRA load/inflation tables, for a given size and pressure the load capacity is identical, regardless of load range. The load range only determines how high the inflation can go, and therefore what the maximum capacity will be.

An Escape 17 generally has a 3500 pound capacity axle/suspension, so the tires need 3500 pounds of capacity per pair, which is 1750 pounds each - plus maybe some extra allowance for even side-to-side loading, excessive speed, accidental under-inflation, etc... although with a GVWR of 3500 pounds, the axle load will never be more than about 3150 pounds if the trailer is properly loaded.

Capacities (from load/inflation tables, e.g. Maxxis)

• ST205/75R14: 1430 lb @35 psi (LR B or higher); 1760 lb @50 psi (LR C or higher)
• ST205/75R15: 1480 lb @35 psi (LR B or higher); 1820 lb @50 psi (LR C or higher); 2150 lb @65 psi (LR D or higher)

It's hard to find ST tires in higher than Load Range C in the 14" size, or higher than Load Range D in the 15" size.

Obviously for the Escape 17 the Load Range B won't cut it, and the 15" tire size provides some extra margin. If you can get LR D in the 15" but not the 14", then the 15" size gives you the option of the higher load range, but the higher load range doesn't provide any benefit if you already have the larger size.

[thoer]

Originally Posted by Brian B-P

... but the higher load range doesn't provide any benefit if you already have the larger size.

Except a tire built to withstand higher maximum pressure/load must therefore be more strongly built. But we've been thru this before, so it is not really worth rehashing.

[Brian B-P]

Originally Posted by Brian B-P

... but the higher load range doesn't provide any benefit if you already have the larger size.

To be more clear, there is a potential benefit of greater resistance to sidewall damage due to likely stronger reinforcement, but any tire will be destroyed by ramming its sidewall into curbs. To offset any of this advantage, the higher-load-range tire will be more expensive and heavier, and will generate more heat at the same load and inflation.

Most importantly, it won't have any more capacity than a lower load range tire at the same inflation pressure.

[fbaggins]

thanks everybody! some good advice.

so here's the back-story ....

we have a 2008 17b, which we bought 3 years ago and share with 2 mutts.
i changed tires 2 years ago, ST205/75R14 C rated CARLISLE RADIAL TRAIL RH,
which is all KAL had locally. (i was in a hurry.)
they seem fine.
the sidewall rating says "1760 lb." @ 50 psi,
which seemed substantial to me at the time.
(but what do i know, this is our first rv.
we have just at this late date graduated from
touring on a pair of very old colnagos and sleeping on the ground in a tent.)
anyhowever,
i saw a nice pair of spiffo aluminum wheels on ebay and started thinking.
but then i figured that it would tie me to 14" forever. so, .......

i was wondering about the advantages/disadvantages of 15".


thanks again all!
very helpful!!

[Donna D.]

Originally Posted by fbaggins

i saw a nice pair of spiffo aluminum wheels on ebay and started thinking.
but then i figured that it would tie me to 14" forever. so, .......

Just pay attention to maximum PSI on wheels, especially the spiffy ones . You may buy tires that have a maximum tire pressure of 50-60 lbs, but the wheels have a max of 35 lbs. And, then there's that offset stuff... I ran into an offset problem when I wanted to use the spare tire on my tug on my Scamp. Drat.

[Brian B-P]

Originally Posted by fbaggins

... i changed tires 2 years ago, ST205/75R14 C rated CARLISLE RADIAL TRAIL RH
...
the sidewall rating says "1760 lb." @ 50 psi

That's Escape's current brand, and the normal load capacity of every ST205/75R14 Load Range C tire.

Originally Posted by fbaggins

...
i saw a nice pair of spiffo aluminum wheels on ebay and started thinking.
but then i figured that it would tie me to 14" forever. so, .......

It does make sense to change to the most desirable size if buying wheels anyway, but since the current tires are only a couple of years old, I would be planning for the tire and wheel choice to change both when the current tires need replacement. Of course, if you stay with 14" you could go ahead and get the wheels now, but you'll need to pay for re-mounting of the tires onto the new wheels.