Should Utility Trailer Spare Tire be Same Size as Current Tires?

Updated 05/03/2018 | Published 05/02/2018

Question:

I have a utility trailer that has 2 each ST205/75D15 tires mounted on the trailer. I have a 3rd wheel that currently has mounted a 205/75R14 yes a 14 inch trailer setup. Bolt holes line up okay. Is it appropriate to use it for an emergency spare or should I buy 205/80D14 to mount or should I buy another 15 inch wheel and tire? Any other thoughts?

asked by: David W

Expert Reply:

I recommend having a spare wheel and tire that is the same size as the wheels and tires currently on your utility trailer; using a different size would create a situation where your suspension would be imbalanced, which you want to avoid even for a short-term situation. You also have different styles of tires on your trailer, and you'll want those to match up as well. Your current tires are bias, which you can tell by the "D" in the 205/75D15 size you referenced, while the 205/75R14 are radials, which does not have a sidewall as stiff as a bias tire.

You will need a wheel with the same bolt pattern as your current wheels, and if you are unsure how to find this, I've added a link to a help article on how to measure the bolt pattern of your wheels. The most common bolt pattern is 5 on 4-1/2" and for that I recommend taking a look at the Loadstar # AM3S640DX, which is a white spoke wheel with a 5 on 4-1/2" bolt pattern and 205/75D15 tire with a load range of C for 1,820 lb maximum capacity at 50 psi.

I've added a link to a video review of this wheel/tire combo as well as a link to each of our 15" wheel and ST205/75D15 tire combos for you to check out as well.

expert reply by: Kyle S