Tires for the PU

[Chuck S]

Camper tires are often "just big enough" to support the axle weights.  My popup grossed about 3500 pounds and was supported by two tires rated at 1660 pounds each or 3320 for the pair.  The remaining weight was on the ball.

This only worked if inflated to 65psi.  At 50psi the tires would only support 1480 pounds (2960 and I know I had more than that on the axle.

-- Chuck

[miataman]

Chuck, I already know what your old popup weighed, since I bought one of your old Duro tires from you about 4 years ago!  (lol)

I did not know LR was tied to inflation - interesting.  One of the reasons I needed that tire from you was that good ole Palomino put the silver sticker on my brand new popup in 2004 that said tire inflation was 50 psi.  Nevermind the max sidewall pressure on the Duros at 65lbs, and that the Pal Mustang weighed in at 3500lbs.  So that tire set at 50 psi started wearing on the slideout side after 1000-2000 miles.  That's when I tuned in here and learned the truth about tires.

Thing is, I haven't seen a link to that elusive LRD radial.  That's the point, for me, and maybe would help the OP.  I would have gone that route, but as you mentioned, they're hard to find.

[Chuck S]

I'd forgotten who I sold my spare Duro tire to.  That's 5 years ago!

Load-Range and Ply-Rating are carry overs from the 1930s.  The important number is carrying capacity and carrying capacity is directly tied to tire construction and tire pressure.

ST Tires are designed to run at full sidewall pressure, not soft passenger tire pressures.  Low tire pressure allows the tire structure to flex and create internal friction which causes heat.  Heat in turn causes the air pressure to rise  Sidewall blowouts occur because the flexing and high temperatures have caused the tire structure to come apart inside the tire.

All tires are designed to run higher pressures than cold tire pressure but when they get very hot the pressure can exceed the design.

Semi tires are almost universally radials.  Pretty sure they use cold tire pressures in excess of 100psi.  There's no "radial bulge" at the bottom.  I have 13" radials on my boat trailer and 14" on my camper.  I touch each tire (and hub) every time we stop.  The Bayside bias tires were hot.  The radials are ambient temperature.

-- Chuck

[outdoors5]

If radials run cooler & better they need to make an ST 185/80R13 tire in load range D.  I can not find them.  Goodyear Marathon are load C in this size.  If anyone can find them please let me know.  I have not paid or picked up my new tires yet. 
     However, I still have one question.  Are you saying that ST radials do not have the weaker side wall that I hear about & possibly allowing sway or other issues?

[sloscheider]

Did you find out if a 14" tire will fit?  It will make your tire life soooo much easier...

[mv577]

My local Tire Warehouse was able to get me two ST185/80D13 LRD for $52.00 a piece just this week... Took a day to come in and 30 minutes to mount etc... Back on my pup the next day...

Maybe an option...

Good luck.

Mike

[Chuck S]

I'm saying that ST radials do not have the weaker side wall that you hear about (I don't know of a reliable source where you'd hear this) and  possibly allowing sway or other issues.  These are NOT passenger car radials which are designed for a soft, comfortable ride.  They should be inflated to maximum sidewall pressure.

-- Chuck

[outdoors5]

It is possible that they were not talking about ST radials & maybe just regular radials...not sure. 

     Oh about going from 13 inch to 14 inch.  I called Coleman & they said if it fits fine but the technician thought a 14 was too large for my camper.  My camper is a 2000 Niagara not the newer highwall larger Niagara.  He was concerned that with a bump in the road I may bottom out.  I have to say there appears to be little clearance with my current 13 tire.

[sloscheider]

bummer

[Chuck S]

In all the years here no one has ever reported successfully fitting 14" wheels and tires to a 12' Coleman/Fleetwood popup and at least one photo essay a couple of years about the failed attempt.

-- Chuck

[miataman]

...and I still wait for the link to that elusive radial 185/80D13 LRD...

[azjim1]

I went through the popup tire search in May and only could find Load Range C 185R13 radials. Ended up with Maxxis from my local Discount Tire who had to order them. I would have liked to upgrade to Load Range D Radials for the extra weight cushion but it was not to be . . . The only Load Range Ds that I could find were Bias Plys.

Of course I discovered that I have been running 175R13 radials for the last 5 years so I probably dodged a bullet with those because I should have been overweight if my trailer was loaded to the max weight rating . . . they were Carlisles by the way.

[CampOwl]

Does anyone use ST145 R12c tires on their pop up? Those things are hard to come by.

[ghacker]

I went through the popup tire search in May and only could find Load Range C 185R13 radials. Ended up with Maxxis from my local Discount Tire who had to order them. I would have liked to upgrade to Load Range D Radials for the extra weight cushion but it was not to be . . . The only Load Range Ds that I could find were Bias Plys.

Of course I discovered that I have been running 175R13 radials for the last 5 years so I probably dodged a bullet with those because I should have been overweight if my trailer was loaded to the max weight rating . . . they were Carlisles by the way.

That was my experience too.

[D-mo]

I just went throught this whole radial vs. bias ply thing with my 13 inch wheels on my Coachman Clipper.  The bias plys where completely shot, and my auto tech suggested I go load C Radial.  After balancing ect. I took them home and compared the spare, which was on the trailer to help support the non-jacked side. 
The radial tire, even tho it is exactly the same size is a larger tire, wider by about 1 inch.  This has caused some issues for me as I now am worried about the exterior of the sidewall hitting my "plastic bolt on flare thingy".  This will be easily remidied with a dremil cutting bit, but a word to the wise, ... these tires are wider/fatter, and a bit taller in my estimations.

d-mo