Upgrading Tires from 15" to 16"- 2006 Cougar 285 EFS

[Texas_Bob_140]

On our annual trip from Double Oak, TX to South Padre Island, TX we blew out two tires and the wheel opening J wrap, fender and wheel well liner and damaged the wheel. The blowouts were within 5 miles of each other. The tires were ST225/R/15/D's. One was a 4 year old Goodyear Marathon with little mileage on it that blew a hole the size of a tennis ball in the sidewall. The second tire was a Mission that had never been used and was the spare and had been covered its entire life. The Mission spare shredded after 5 miles and caused the damage. Weight on the tires is around 8,000 lbs. as measured on the Cat scale at the local truck stop and all tires were aired up to 65 PSI. I also have Tireminder sending units on each tire and there was no warning of any problem.

I'm planning on upgrading to a 16" wheel with a BFG Commercial T/A LT225/R/16/E tire. The BRG's have a diameter of 29.4" per BFG and the Goodyear ST's have a diameter of 28.3" Center to center distance on the tandem axles is 33" so I will have clearance between the wheels of about 3.6". There is plenty of room between the ST's and the frame of about 3". I have checked out the slide out mechanism and the closest the slide out bar/track comes to the ST tire is somewhere between 5 1/2 to 6 inches.

The limiting factor seems to be the distance from the tire to the wheel well liner. On the present ST's, the distance is 2 1/2" With the LT tires, that should be reduced to about 2". Interestingly, there is no real liner on this trailer - it appears to be plastic coated fabric which looks like the cheap plastic coated tarps they sell at the home stores.

I will be replacing the wheels with 80 PSI wheels and metal valve stems.

Any thoughts or counsel, especially anyone who has made this modification to this year and model trailer, is appreciated. Thanks.

[Dixon_Mark]

I upgraded to the 16 inch wheel and used 225-75-16 tires. I originally went with the bfg commercial ta tires but after 2 years I had a belt separate. This was the third commercial ta this has happened to me with the other two were 265-75-16 on the front of my box truck. I called and talked to bfg due to them already having a recall on that brand tire for this issue but none of my tires sizes were on the list.But they ponied up and paid 95% of tire replacement for any Michelin tires I wanted. I now have a set of Michelin ribs on the trailer. Cost me out of pocket around $150.00 for mounting and balancing with new metal valve stems.I am a happy customer but I will not be buying any more commercial ta tires.

[jaycocamprs]

4 years ago I did what you want to do. We put LT235/85R16E BFG's under our 07 Jayflight. Now the Jayflight had the ajustable spring hangers, but we still only had about 2" over the tires and in 2 years never showed any signs of contact. 2 years ago we traded for the Mountaineer we have now, the BFG LT's are under it now and still doing well.

[Texas_Bob_140]

Thanks to all for your comments and questions. With reference to moving the bolts on the hangars, no options exist on this trailer.

With reference to the comment "The most common mistake made with an upgrade such as the OP is making is tire pressure", here are a few facts that I did not originally clutter up the first post with.

1. The placard calls for a 225/15/R/D tires inflated to 65PSI.
2. At 2540 lbs. capacity per tire, I should be able to carry 10,160 lbs. capacity on four wheels. Granted, there could be some weight differences per wheel.
3. The placard says the axle rating is 4400 lbs. per axle which is 8800 lbs. for this two axle trailer.
4. The weight on the two axles is 8000 lbs. per the CAT scales at the truck stop.
5. In order to go to a larger 16" rim with a tire that has roughly the same profile as the original tires and will mount in the same space as the original tires, a LT 225/16/R/E is rated at 2680 lbs. at 80PSI. That's why I will go to 80PSI.
6. While I would like to have more reserve capacity, given my space requirements
and not wanting to change the geometry of the trailer i.e. blocking the axle, with the LT225/16/R/E tires, my reserve capacity over the GVWR of 9960 lbs. is approximately 760 lbs.
7. As to the comment, "Industry standards tell us to use the amount of tire pressure needed to provide the load capacity recommended by the vehicle manufacturer", it is my belief therein lies the problem. There really are no comprehensive standards for trailer tires and the manufacturers that outfit their trailers with poorly made offshore tires are not doing anything to raise the standard for ST tires.

I didn't want to rant on in my original post but I can say that the experience with Goodyear has been dismal. We have towed about 75,000 miles over 13 years. In those years Goodyear replaced four tires they made for Carlisle and the damage on my 24' Wilderness pull behind. On the 5th wheel over the last six years, they have replaced four tires and paid for the blowout damage caused by the blowout, two years later replaced two of the latest tires because of sidewall defeciences and now I have another blowout. So at this point, I have a four year old tire blowout, and one four year old tire still working and two each two year old tires. The 5th wheel has only about 25,000 miles on it. And I do check my tires every time we change locations. The newer tires came without a warranty, so two tires will be presented for warranty when we get home.

Enough said, I think.

[F4whlr]

If its any consolation, I changed my ST225/75R15 LR/D tires to larger Maxxis ST 235/80R16 LR/E radials...couldn't be happier. I used the specs of newer Cougar fifth wheels for reference.

[FastEagle]

The most common mistake made with an upgrade such as the OP is making is tire pressure. Lots of people will say to set your air pressure to the heaviest tire weight. When that recommendation is followed there is zero load capacity reserves for that tire. The slightest drop in air pressure for that tire puts it in an overloaded condition.

Industry standards tell us to use the amount of tire pressure needed to provide the load capacity recommended by the vehicle manufacturer. Look on the tire placard/certification label for that recommendation. In most cases - if available - an extra 5 psi will provided much needed reserves for the unpredictability of load variations with the RV trailer.

FastEagle

[1971duster340]

I went from 15" Marathon D rated to 16" Michelin RIB E rated. Took 3 blowouts at different times to confirm the Goodyears just weren't up to it. Each axle/tire was loaded 85-90% capacity with the D ratings. I think Marathons aren't up to that % of constant loading. I liked the feel the RIBs provided and the peace of mind of the extra capacity helped too. Physical size was close enough after the upgrade, I didn't have to do any adjustment to the DualCam WD system.

[laknox]

Texas Bob 140 wrote:
On our annual trip from Double Oak, TX to South Padre Island, TX we blew out two tires and the wheel opening J wrap, fender and wheel well liner and damaged the wheel. The blowouts were within 5 miles of each other. The tires were ST225/R/15/D's. One was a 4 year old Goodyear Marathon with little mileage on it that blew a hole the size of a tennis ball in the sidewall. The second tire was a Mission that had never been used and was the spare and had been covered its entire life. The Mission spare shredded after 5 miles and caused the damage. Weight on the tires is around 8,000 lbs. as measured on the Cat scale at the local truck stop and all tires were aired up to 65 PSI. I also have Tireminder sending units on each tire and there was no warning of any problem.

I'm planning on upgrading to a 16" wheel with a BFG Commercial T/A LT225/R/16/E tire. The BRG's have a diameter of 29.4" per BFG and the Goodyear ST's have a diameter of 28.3" Center to center distance on the tandem axles is 33" so I will have clearance between the wheels of about 3.6". There is plenty of room between the ST's and the frame of about 3". I have checked out the slide out mechanism and the closest the slide out bar/track comes to the ST tire is somewhere between 5 1/2 to 6 inches.

The limiting factor seems to be the distance from the tire to the wheel well liner. On the present ST's, the distance is 2 1/2" With the LT tires, that should be reduced to about 2". Interestingly, there is no real liner on this trailer - it appears to be plastic coated fabric which looks like the cheap plastic coated tarps they sell at the home stores.

I will be replacing the wheels with 80 PSI wheels and metal valve stems.

Any thoughts or counsel, especially anyone who has made this modification to this year and model trailer, is appreciated. Thanks.

FWIW, my 11,300 GVW FW came with 5,200 lb axles and D-rated tires. I had one failure my 2nd year < 1,000 total miles. I replaced it with another D-rated tire and ran them another 2 years when the other 3 separated and I replaced with a set of Greenball E-rated tires. These all failed after 5 years and I put on a set of the new Carlisle E-rated tires, when I couldn't get the Maxxis I really wanted. I was lucky in that my aluminum wheels were rated for 80 psi and I didn't have to swap. If you =know= your rims are 65 psi, the switch to 16" wheels is the best way to go. If they are already 80 psi wheels, consider using the Maxxis to save some bucks.

Lyle

[rseymour21]

I have a 08 cougar RK, upgraded about a year and a half ago from 15" to 16" LT tires and couldn't be happier. I thing I did at first was running much higher tire pressure, around 70 to 75 psi. But after a couple trip, I had a lot of bounce/rough ride. I thought about it and figured if 65 psi was good for the 15", then 65 psi is good for the new tires.

You should certainly go to 16"!

[TriumphGuy]

You will probably be fine with the reduced clearance. Looking at trailer suspensions it doesn't seem like they have nearly the amount of travel that car/truck suspensions do.

I did the upgrade but used 245/75R16s because I had a great deal on a set. I ended up raising my trailer (next holes on spring hangers) but I think I didn't need to. I'm contemplating dropping it back down because of issues with the entrance steps being too high.

I've been on the 16" wheels and tires for years and have not had any issues. When I was on 15" tires, it was about 1 tire blown a year. This was on about 4 different campers ... it's nice to leave the STs behind and have a quality LT tire.

[Peg_Leg]

If those have 10" brakes, just go ahead and upgrade to 12" and get 6 or 8 lugs to match whatever wheels you find.

[Lantley]

After numerous issues, I did the same mod to my 2006 11K GVW TT.
Tire problems solved. You will not regret it.

[JIMNLIN]

Texas Bob 140 wrote:
The bolt pattern is 5.5"-6 lug and is available on the internet from multiple sources. I buy from Southwest Wheel which is in Dallas and also on the internet. My main concern is whether the 2" clearance from the tire to the wheel well is sufficient.

Welcome to the forum.
I had the same issue. My used 11200 lb trailer came with new ST225/75-15 D Marathons the dealer had just installed on 5200 lb axles. My Goodyear truck tire dealer gave me a great deal on swapping to 16" LT215/85-16 E at 30.4" tall.
I have 1 3/4" at the top of the tire and 1" on the inside. The tires tread have rubbed the sheet metal liners slightly when crossing a ditch and one wheel goes all the way down forcing the other up into the wheel well but never touch on the road at speed in any situation. No issues from the light rub.

Sound like a good plan for 6-8 years and 40k-60k miles of trouble free tire issues.

[bogart661]

I did this in 2009 with my old 5th wheel, a 2001 McKenzie Lakota. Like you the only clearance issue I had was from the top of the tire to the bottom of the wheel well, my axles were already flipped so I had 2 inch solid steel blocks added to rise the trailer and that gave me the clearance I needed. I had at least 6 blowouts with the ST tires, after changing to the BFG Commercial T/A's I had none.

[C_Schomer]

I got the 5.5x6 wheels from etrailer $195 and 16" LTEs for $605. Craig