I am confused about wheel width. I was running 35x12.5x18 Nitto Mud Grapplers on an 8" rim. I then upgraded to a 9" rim, and using the Kenda KR29's that are 35x12.50x17. So I went with a smaller diameter wheel but wider.

Somehow after I mounted the Kenda's on the wheel they came up much skinnier than my mud grapplers. They almost look like 10.50's. They measure probably 2-3" thinner than my mud grapplers.

How did this happen? Could it be bc they are not actually on the truck under load?

 

Pic for reference

 

I have 36x12.50x15" swampers that measure 37" tall and 14 inches wide when mounted and installed. Where as my mickey thompson mtz were surprisingly the 35x12.5 they advertised. My cooper discoverer st maxx are 34.5x11.5 even though the sidewall says 35x12.5. The size on the sidewall is only a rough guide.

 

That's unfortunate. I would expect a small difference but the new tires are thinner by several inches.

Anyone interested in a set of Kenda's? lol

 

Two different manufacturers.
Pretty common. Unless made by the same company, there is a variance.