Wheel and Tire Upgrade (thread 2)

[Saluki86]

I tried to respond to a thread titled the same as this that was posted in 2012 but for some reason I am getting an error.  Anyway, trying a new post.......?

Going to upgrade all 3 tires on my C16.  All three that came with it when I bought it are different....different load ratings, plys, etc.

One of the tires is "5.70-8".  I thought the "8" meant it was an 8" tire but when I put a tape measure across the rim to measure the diameter, it was 9".

So, can someone:
- Explain the number on the sidewall and how to tell what size I have.
- I wanted to go to larger tires/rims.  Perhaps 10" if these are 9".  I saw MacGyvers suggestion on etrailer and think I am gonna go that route but would listen to other suggestions.

In case it is important, the trailer is a Magic Tilt and I have Bearing Buddies on it.

Thanks,
Saluki