Selecting Trailer Tires with Suitable Weight Capacity and Speed Rating for Highway Use

Updated 05/17/2018 | Published 05/16/2018

Products Featured in This Question

Karrier ST225/75R15 Radial Trailer Tire - Load Range E

(2300)

$165.77

Westlake ST205/75R15 Radial Trailer Tire - Load Range D

(545)

$139.32

Provider ST205/75R15 Radial Trailer Tire - Load Range D

(1099)

$138.29

Question:

Hello, I am looking for advice for a set of replacement tires 4 + 1 spare that will be used on a tandem axle 6 lug flat bed trailer with “ Heavy Duty” axles. Here are some details: The previous tires were 7.00”-15” tires on steel 6 lug 15”x 5.5” rims. Currently 205/90/D15 ST tires are on the same rims. Is a bias ply or radial Load Range “D” or “E” “Highway Speed” rated tire is available? The trailer is used occasionally to haul a tractor and autos to classic car shows. I would like to retain a high load rating while still having the high speed rating while traveling on the interstate with a unloaded trailer. Thanks in advance.

asked by: Chris L

Expert Reply:

Your trailer's 15 x 5-1/2-inch rims can accept two tire sizes, 7.00-15LT light truck tires and ST205/75-15 special trailer tires.

In terms of maximum load capacity the 7.00-15LT light truck tires in load range E can handle the most weight, 2,403 lbs at 70 psi, while the highest-rated ST205/75-15 tire can handle 2150 lbs at 65 psi pressure. You want to choose four tires that in total can handle the GVWR of your trailer; find that GVWR figure and divide by 4 to find your minimum load requirement per tire.

In the ST205/75-15 size you have a choice of bias ply or radial construction; radials will typically offer a higher speed rating and be better suited to highway use. For a Load Range D radial with an M speed rating (good to 81 mph) you can use Provider ST205/75R15 Radial Trailer Tire # TR20515D or Provider ST205/75R15 Radial Trailer Tire # TR20515D. For a tire rated for 75 mph we offer # LHWL300.

Do please note that ALL trailer tires should ALWAYS be inflated to the maximum COLD psi pressure noted right on the tire sidewall. It is never appropriate to under- or over-inflate a trailer tire for any reason.

The main reason any trailer tire will fail is excess heat. The three main causes for a tire to overheat are 1) incorrect inflation pressure; 2) overloading beyond the rated weight capacity; and 3) driving faster than the tire's rated maximum speed. All three of these issues generates heat; all three at once all but guarantee a tire failure.

The linked articles on special trailer tires may be of interest to you.