The nice weather is
here and many trailers are hitting the road with spring projects. Are your trailer tires in need of replacing? Until recently, Tire Rack only carried the Goodyear Marathon Radial trailer tire. For information on this Trailer Service tire, read my previous blog post, "Trailer Tires are Available at Tire Rack."
We now offer a few more tires in this performance category, including our newest option, the Power King Towmax STR. Like the Goodyear Marathon Radial, the Towmax STR tire is designed for use on campers, boat trailers, fifth wheel trailers and even some larger utility trailers. The tires also share some common design features, such as a symmetric tread pattern and twin steel belts with reinforced nylon caps to help increase overall durability.
Unlike the Marathon Radial, the Towmax STR is produced in the popular 235/85R16 load range E size that many full-size trailers use. Another unique application is the 225/75R15 size that's available in an E load range versus only a D load range with the Goodyear Marathon Radial.
Listed below are the available sizes for the Power King Towmax STR trailer tire:
- ST175/80R13 C
- ST185/80R13 C
- ST205/75R14 C
- ST215/75R14 C
- ST205/75R15 C
- ST205/75R15 D
- ST225/75R15 D
- ST225/75R15 E
- ST235/80R16 E
- ST235/85R16 E
Trailers will be more stable and pull better on tires designed specifically for trailer use. Special Trailer tires are constructed with heavier duty materials and are tougher than typical passenger vehicle tires. To gain a better understanding of the driving requirements of Special Trailer tires, read "Trailer Tires vs. Passenger Vehicle Tires."

Yes, all of the Power King Towmax STR Trailer tires are radial tires.
I would feel okay using that spare given that has been protected from sunlight and the elements for most (if not all) of its life.
I would like to upgrade to an E load rating. There isn't much extra room in the wheel wells for a 15" tire.
Can I get a 14" E rated tire? If not why not? Many trailers use the 215 14" tire and they are almost overloaded empty. This needs to be rectified.
I'm sorry, I have not heard of any E load range 14" tires, sorry.
I do not show any more XL tires available in 285/50R20. Most other tires in this size carry less than 2500lbs per tire so I could not recommend them. There are still many load range E tires made in 16" sizing, so you may want to consider going that route, or modifying your fenders to help with the rubbing on your current size.
Industry standards dictate tires with the ST designation are speed rated to 65 MPH.