Will Tire Size 225/75-15 Replace a Size 7.00-15 Tire

Updated 04/05/2013 | Published 04/02/2013

Products Featured in This Question

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

(2300)

$168.17

Loadstar ST225/75D15 Bias Trailer Tire - Load Range D

(3846)

$145.79

Question:

I have the firestone transport tires 7.00-15lt on my tandem trailer 25ft cabin cruiser I need to replace them but have notice that the 7.00 only has a weight capacity load of 2040 capacity@60psi. Now I would like to know if I can place the ST225/75R15D tires on the same rims as those of the 7.00 tires? and how about the E instead of the D on 225/72/15? isnt the rated E better than the D?

asked by: Carl

Expert Reply:

Based on my research, 7.00-15 tires typically fit a 15 x 5-1/2 inch wheel. The ST225/75R15 tire size will fit on 15 inch diameter rims that are 6, 6-1/2, or 7 inches wide. They will not fit on rims narrower than 6 inches. I recommend checking the width of your rims to determine if the new tires will fit. Another thing to note when moving to a different tire size is fender and frame clearance. The 225/75-15 tires are going to be slightly shorter and wider than your current tires.

A 7.00-15 tire will be about 7 inches wide and have an overall diameter of about 29 inches. The overall diameter of a 225/75-15 tire is about 28 inches and it will be about 9 inches wide. This means the new tires will sit about 1 inch closer to the inside of your fender or trailer frame. I recommend measuring the space you have available to make sure a wider tire will fit.

Keep in mind, increasing the weight capacity of your tire will not increase the weight carrying capacity of your trailer. You will be limited to the weight capacity of your axles. Going with a load range E tire, like part # AM10303, is not necessarily better than a load range D tire, like part # AM1ST96, if the load range D tire meets or exceeds the weight capacity of your axle. The load range E tire will have a stiffer ride from a D tire.

If your wheels are 5-1/2 inches wide, then you could use the Kenda Light Truck Tire, # AM10414. This is a load range E tire with a 2,376 lb weight capacity at 70 psi and fits a 15 x 5-1/2 inch rim. If your wheels are less than 5-1/2 inches wide, then let me know the size of your rims and I can make a more specific recommendation.

expert reply by: John H