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Old 08-31-2012, 06:02 PM   #1
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Tires and Wheels

I have a 2007 28' Rockwood 5th wheel with tire sizes for 15" wheels 205/75/15 load rate C (50PSI). I need new tires and would like to upgrade to a D load tire wich will carry a heavier load. What is the best make of tires for this application considering increased air pressure for my mag wheels? Do I have to go to 16" wheels? Would they even fit my RV? How about going into a LT tire? I am looking forward to some answers to my questions.

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Old 08-31-2012, 06:45 PM   #2
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Your ST205/75-15 C has 1820 lbs of capacity x 4 = 7280 lbs for a tandam axle trailer.

If it was my trailer I would look into mounting Goodyear Wrangler H/T or a commercial grade Maxxis U-168 A LT215/75-15 D at 2095 lbs. Both tires require a 65 psi rated wheel and are popular with trailering public.

Also there are many usa branded LT235/75-15 C at 1985 lbs capacity . They are a bit taller so you will have to do your own measuring for proper wheelwell clearance issues.

I notice the Yokohama RY215 in a 700R-15 load range D at 2040 lbs are popular with the boat trailering crowd.

Any 16" (2680-3042 lb capacity) IMO would be overkill for a trailer that needs 1820 lb per tire. Trailer tire operate in a extreme invironment and work best with max pressures unlike a tow vehicle.

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Old 09-01-2012, 02:53 PM   #3
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If your rims have the load capacity and pressure ratings for the increased pressure of the LRD tires they would be your most economical upgrade. They are identical in size insuring easy fitment.

In the reference you can compare sizes and load capacities. The reference is not an endorsement for that brand of tires. Itís just what it is, an informational reference.


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Old 09-02-2012, 12:31 PM   #4
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Another option is the Continental Vanco2 LT225-70-R15D 27.4 in high (vs 27.1 for 205-75) 9in wide vs 8in (1/2 ib each side this would be the measure and remeasure for me) 2470lb at 65psi..

I run 80psi tires on stock wheels, trailer came with 65psi tires.. no pressure related problems in 3 years.. with all of the 15in ST tire (China Bombs) issues on the RV boards, when was the the last time you read about a rim failure? (I do run all steel valve stems)
I will be trying the Continental LTs when my lstill new Carlisles separate.
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Old 09-02-2012, 03:06 PM   #5
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Originally Posted by pitch View Post
I have a 2007 28' Rockwood 5th wheel with tire sizes for 15" wheels 205/75/15 load rate C (50PSI).
Typical. Not enough extra tire weight capacity for that much trailer.

My 5er came with those same tires. And the 5.5" wide wheels that were okay for those tires but not for the ST225/75R15 I wanted. So after blowing out two tires on the first trip, I bought new wheels that were 6" wide:

The bigger tires on wider rims fit inside the wheel wells of the trailer with rubbing only if I hit a really severe bump. So don't hit any really severe bumps!

I went with Maxxis ST225/7R15D tires. No more trailer tire troubles. Maxxis makes ST225/75R15E trailer tires too, but I didn't need more than the load range D.

If your careful measurements convinces you that you don't have room for ST225/75R15 on 6" wde rims, then back off to ST205/75R15D on your stock rims. Those have 2150 pounds weight capacity @65 PSI, which is a lot more than you have now.
M8008 ST Radial

The Power King Tomaster tires that FastEagle linked to are the famous "China bombs" that a lot of folks complain about. I don't have any experience with those, but I have Maxxis ST225/75R15E on my cargo trailer and Maxxis ST 225/75R15D on my 5er, with no complaints.

My new TT came with more than enough tire weight capacity for the trailer (7,000 pounds tire capacity vs. about 5,000 pounds max load on the tires). But I'll still probably replace them with more tire when the first one of the stock Marathon ST205/75R14 tires blows. I have over 5,000 miles on those tires now with no problems, so maybe Goodyear has figured out how to build a trailer tire that won't blow up on the first long high-speed trip.
Grumpy ole man with over 50 years towing experience. Now my heaviest trailer is a 7,000-pound enclosed cargo trailer, RV is a 5,600 pound Skyline Nomad Joey 196S, and my tow vehicle is a 2012 F-150 EcoBoost SuperCrew.
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