Can I use a st2257515 on a trailer that has st2057515 on it for a spare if I end up with a flat on one side? I know it is not ideal. But would it work if i end up in bfe with a flat?

It'll be fine for a short time. I wouldn't load it to max & run down the interstate, but you can limp it home.

How much tire clearance do you have on both sides if the wheel width is different?
I believe that first number is the tire diameter so that puts a bit more load on the larger tire but a 215 has a higher load rating than a 205.
Be sure to always check the spare pressure. lots of people find the spare is low or even flat when they're on the side of the road.

It depends on clearance of trailer on both sides. there is roughly .800" with difference in width. I have a utility trailer that even one size up would not work, let alone two sizes up.

Ok guys, good info. I appreciate it very much.

quote:

Originally posted by 220-9er:
How much tire clearance do you have on both sides if the wheel width is different?
I believe that first number is the tire diameter so that puts a bit more load on the larger tire but a 215 has a higher load rating than a 205.
Be sure to always check the spare pressure. lots of people find the spare is low or even flat when they're on the side of the road.

The first number is actually the Tire 'Section' Width. In this case, 225mm vs 205mm, so an increase of 20mm or approx. .8" in width.

The second number is Aspect Ratio, which determines the Sidewall Height, and here, it's 75% of the Tire Width. In this case, 168.75mm vs 153.75mm, so an increase of 15mm or .59" of sidewall height.

Tire Diameter = 2x Sidewall Height + Wheel/Rim Diameter, so...

For the ST225: 2*168.54mm = 13.29" + 15" = 28.3" Diameter vs. the ST205: 2*153.75mm = 12.11" + 15" = 27.1" Diameter, means an increase of 1.2" Tire Diameter.

If the trailer was new to me I'd jack it up in the driveway and try the spare. You are assuming the wheel is the right bolt pattern. If it goes on you're good to go.