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Author Topic: Changing wheel size on fifth-wheel  (Read 276 times)

Bob Taylor

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Changing wheel size on fifth-wheel
« on: August 11, 2017, 12:44:38 PM »
Any experience changing wheel size from 15 inch to 16 inch?  I have a 2002 HR 28 (29 1/2 ft.) Alumascape that I ordered new.  Still in good shape and with the price of new units, I am planning to keep it several more years.  Problem with tires not lasting but a couple years and having blow outs.  Check tires regularly before and during travel.  The last was about 1 1/2 year old load range E, Trailer King tire made in China. 
A RV Tech has suggested going to a 16 inch wheel and replacing tires with a Firestone LT highway tire (I don't remember particular one) in load range E.  I have 33 inches from center of axle to center.
The trailer is 8700 lbs. dry weight and 2159 lbs. carrying capacity after water and propane added.  It is not overloaded.
Any advice?

grashley

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  • Western KY for now.
Re: Changing wheel size on fifth-wheel
« Reply #1 on: August 12, 2017, 06:25:35 PM »
Welcome to the Forum!

There are several factors which affect this switch.

Are there 16" rims that fit your bolt pattern?  If not, new drums are part of the picture.

Make sure the new rims will carry the pressure of the new tires.  Some rims are rated at 50 psi, others at 85 psi, etc.

Make sure the DIAMETER of the new tires will fit in the wheel well and not rub the camper or the other tire.

LT tires come in many sizes and load ranges.  Sizes affect diameter.  Load range affects load carrying capacity.  Your TT weighs about 10,000 # loaded.  Assuming 1,000# hitch wt, that leaves 9,000# on the two axles or 2250# per tire.  That is an absolute minimum!!  Tires last longer if they are not loaded to capacity, so tires with at least 2500# max load are much preferred.

You did not specify the size of the current tires.  If you provide that, I will be glad to calculate the diameter and suggest 16" tire sizes with a similar diameter.  Unless you are a math nerd, reading the calculation will give you a headache!

This switch has been done before, but it is important to get it right!
Preacher Gordon
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It's not a dumb question if you do not know the answer.

longhaul

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Re: Changing wheel size on fifth-wheel
« Reply #2 on: August 12, 2017, 10:37:56 PM »
Quote
A RV Tech has suggested going to a 16 inch wheel and replacing tires with a Firestone LT highway tire (I don't remember particular one) in load range E.

 The Firestone Transforce HT in a LT225/75-16 E has 2680 lb capacity and is 29.3" in diameter. These tires are popular on commercial haulers web sites and a favorite  with rv folks also.

 Other  popular LT brands for trailer use in several sizes;
 Cooper Discoverer HT-3.
 BFG Commercial T/A 2 in the AS tread.
 Goodyear Wrangler HT.

 And if you want a commercial grade all steel carcass the Bridgestone R-250 and the same old time favorite commercial grade Michelin XPS Ribs. Both are considered the holy grail by experienced trailer owners (rv and non rv trailers) for 5k/6k axles.

 My 11200 lb 5er came with ST225/75-15 D at 2540 lbs capacity. I went to 16" trailer wheels and LT215/85-16 E at 2680 lbs capacity.  Ran two sets of BFG Commercials at 55k and 52k miles...no issues.  I now have new Firestone Transforce HT on the trailer.

Gary RV_Wizard

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Re: Changing wheel size on fifth-wheel
« Reply #3 on: August 13, 2017, 10:37:52 AM »
So far the only problem I'm hearing is that the el cheapo Trailer King tires didn't last. Not sure that requires a tire diameter change to fix! How long did the original tires last? And how did they fail? Are they wearing unevenly, blowing out, or what?

You could upgrade the tire diameter, or buy better grade of tires in the current 15" size. You could also change the 15" to a slightly wider or higher profile size to gain some load capacity. Chances are the OEM tires were barely adequate for the trailer GVWR, so a bit extra capacity can be a plus. Odds are you have plenty of room for a slightly wider tire and at least a little more diameter.

You probably have ST tires now and those are typically limited to 65 mph. If you went to 16" you could probably get an LT tire large enough for the load and increase the speed rating to 77. However, there are some brands of St tires now rated above 65 mph, e.g. many Maxxis brand models.

You only mentioned 15" and LRE.  What specific tire size do you now have?
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

donuts

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Re: Changing wheel size on fifth-wheel
« Reply #4 on: August 13, 2017, 01:21:21 PM »
Have you looked at Goodyear Endurance ST tires? They are the only trailer specific tires that I know of that are made in America. I have them on my 5th wheel and they are so far very good. Then again, the other 2 tires are Goodyear Marathon and I have never had a problem with those tires either.
I would at least look at the Endurance product.

Stan
Stan and Cindy
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skeeter_ca

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Re: Changing wheel size on fifth-wheel
« Reply #5 on: August 18, 2017, 12:21:18 PM »
I just put on 4 Goodyear Endurance tires because i heard of all the problems with the cheap chinese stuff. Didn't want to have that problem with our first big trip. Went 4500 miles with not one problem.

skeeter

skeeter_ca

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Re: Changing wheel size on fifth-wheel
« Reply #6 on: August 18, 2017, 12:26:42 PM »
I was considering upgrading to a larger size also. The next size up was a 16" and i had about 3 inch clearance between the tires when on level ground. The 16's would have added about 2inches to the diameter so it looked like it would fit. Then i noticed as i drove and hit different angles with the tires, went up bumps and such the gap changed significantly down to almost 1/2" at some times. If i had replaced them they would have been rubbing and locking up together. So look out for that. Glad i didn't

skeeter
« Last Edit: August 18, 2017, 12:31:14 PM by skeeter_ca »

QZ

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Re: Changing wheel size on fifth-wheel
« Reply #7 on: August 21, 2017, 10:33:51 PM »
I went with 16 Firestone Transforce HT(?)  Far less sway compared to the old Marathons. We just put Carlisle HD on my sons FW and iirc they were rated at something like 3500 Lb.  I dont remember what my Transforce are but not near the Carlisle. You wont go wrong with 16's.

I also have the 33 in axle spacing where my sons is 35 inches. 

 

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