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Recommendation for Upgrading Tire and Wheel Size on Trailer with Flipped Axle


Hi! I have a 2015 Flagstaff 176 Ltd popup camper. The camper currently has a 2000lb Dexter axle with 5x4.5 hubs, 72 hub face and 58 spring seat measurements. It also is currently sitting on ST145r12 radials rated at 1220lbs at 65psi. I have ordered new 1 3/4 spring seats and new u-bolt kits to do an over-under axle conversion for added ground clearance. Also, both of my tow vehicles have minor lifts on them and I would like it to tow more level than it does currently even with a /rise hitch. My research to this point says that particular axle is capable of a 12-15 Rim size. I was looking for recommendations on larger tires I could run on a 15 Rim, currently looking at some in the - 8 to - 10mm offset range with the 5x4.5 bolt pattern. The rims are available as a 15x8 or 15x9. I realize my wheel wells might be a limiting factor, but couldnt find anything to even give me a rough idea of possible tire sizes after the axle flip. Also, trailer weight is ~1346lbs dry. Would I be able to run an LT tire assuming proper inflation to account for the weight per tire? I just have bad experience with traditional trailer tires in general... Also, wouldnt mind having a little bit more aggressive tread pattern for washboard roads and muddy camp sites. Thanks!


Expert Reply:

Since you are flipping the axle on your 2015 Flagstaff Pop-Up Camper, going to a larger tire and wheel size should not be an issue. As you mentioned, you will just need to make sure you have the needed clearance on your trailer, specifically within the wheel wells. When moving the trailer's leaf springs to above the axle, the trailer is going to essentially be lifted by the width of both the axle and the spring stack.

Your existing ST145/R12 tires have an overall diameter/height of 21.3 inches and a width of 5.7 inches. If you were to go with a 15 inch tire, such as the Provier ST205/75R15 Radial Trailer Tire w/ 15 Inch Wheel # A15R645SMD, its overall diameter height would increase to 27.1 inches with a width of 8.1 inches. Even when flipping the axle on your trailer, this is a significant jump in size. You will need to make sure you have the clearance necessary for both a 5.8 inch increase in height and a 2.4 inch increase in width. Note that you will want at least 3 inches of clearance between the top of the tire and the fender.

If you don't think you will have the needed clearance, a better option might be to go with a slightly smaller 14 inch tire like the Provider ST205/75R14 # TTWA14RSM. This will have an overall diameter of 26.3 inches and the same width of 8.1 inches. This radial ply tire has a maximum load of 1,760 pounds at 50 psi and a maximum speed of 81 mph.

I do not recommend going with LT tires on your trailer. Only Special Trailer (ST) tires should be used on a trailer, as they feature stronger sidewalls that are specifically designed to handle the higher loads that a trailer will provide. Also keep in mind that trailer tires should always be inflated to the maximum psi as listed on the sidewall.

I have included a couple short video demonstrations on the tire and wheel combos referenced, along with a couple articles on trailer tires that you might find helpful.

expert reply by:
Chris R

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