Differences Between Special Trailer Tires & Passenger Vehicle Tires

Updated 10/18/2016 | Published 10/17/2016

Products Featured in This Question

Karrier KR18 ST235/85R16 Radial Trailer Tire - Load Range F

(2519)

$208.77

Provider HD ST235/85R16 Radial Trailer Tire - Load Range G

(267)

$315.48

Question:

I am needing a spare tire for my stock trailer. The tires that are on it now are 215 85R 16 size. I was told that these are not trailer tire size. Can i get a 235 80R 16 for my spare? I plan to change all to a Trailer tire size. Thanks

asked by: CD

Expert Reply:

Size is not what distinguishes a trailer tire from a passenger car tire. The same size tire could be produced as either a vehicle tire or a trailer tire. What makes a trailer tire different is construction. Special trailer (ST) tires have stiffer sidewalls that are able to better handle the vertical loads from trailers, while passenger (P) car tires, especially radials, have more flex in the sidewalls to give them better traction and cornering ability.

ST tires should never be used on a vehicle and P passenger car tires should never be used on a trailer.

We do not offer special trailer tires in your 215/85R16 size. All trailer tire sizes we carry are shown on the linked page. These do include the 235/80R16 size and we have four such tires available, all in Load Range E.

Your current size 21585R16 tire has an overall diameter of approximately 30-1/2-inches. The wider ST235/80R16 size like # TTWPRG235R16 will be 34-1/2-inches overall diameter and it will be 3/4-inch wider too. Since this is a large increase in size you need to make sure you still have adequate clearance in the wheel well. You also want to match your tire choice to the axle's weight rating.

Trailer tires should always be fully inflated to the maximum psi pressure rating that is indicated on the tire sidewall. It is never appropriate to under- or over-inflate a trailer tire.

expert reply by: Adam R