Comparing a 185/80-13 Tire to the 175/80-13 Size on Americana Trailer Tire AM1ST77

Updated 03/24/2025 | Published 03/13/2013

Question:

what is the difference in height of a p185/80r13, and a 175/80d13? Thanks

asked by: Syeven C

Expert Reply:

In height or total diameter, a 185/80-13 and 175/80-13 like part # AM1ST77 only differ by about 5/8 of an inch. The 185 would have a diameter of 24.65 inches while the 175 would have a diameter of 24.02 inches.

The section width, or thickness of the tires differs is slightly more noticeable. The 185 would be 7.28 inches wide while the 175 is 6.89 inches wide.

Take a look a the FAQ I have linked for more information on tire sizing.

expert reply by: Sarah L

Billy C.

3/24/2025

Would the 175/80/13 work for a trailer spare on a trailer that has 185/80-13 tires?

Kate F.

3/24/2025

@BillyC Hello Billy, Yes, a 175/80-13 tire can be used as a spare for a trailer that normally uses 185/80-13 tires, but it's a bit smaller and not a perfect match. It's about 10 mm narrower and a little shorter in height, which means the trailer might sit slightly uneven, especially if you have two axles. That’s okay for a short trip to get you off the road or to a tire shop, but it’s not great for long-term use. Also, 175 tires usually can’t carry as much weight, so make sure it’s strong enough for your trailer. In short, it works as a backup, but try to match the original size when you can. What kind of trailer were you looking to use it on?