So, in my quest to upsize to 35x12.50 R17, I have been reading countless of threads.

I really like my current KM2 285/70/17, which according to Tire Rack (and BFG) measure 33x11.5". I keep reading that these run small, so I measured my spare, on a 17x9" wheel, aired up to 37 psi (guessing that's about where the manufacturers measure a 17" tire).

I ended up using a level and measured to the bottom of the level, which is the top of the tire. These tires have about 5K miles on them, and I still got a measurement of 32.75". Mounted on the Jeep, the other KM2s measured 32.25". Seems like you get pretty to close to what they claim, don't you?




And here, next to a 35x12.50 R17 Wild Country MTX (about 1/4" shorter than a brand new spare [trying to compare used to used]).


The new Wild Country spare measured at 34.25" (the used at just under 34"), but I'd expect another 1/4-1/2" increase once mounted and aired to 35-38 psi, right? Then an approximate 1/2" squat, once mounted on my Jeep? I've seen sites that list the WC tire at 34.50" - 34.80" tall.

 

Yeah I heard KM2's are actually undersized too. I also run 285/70 17's. Looks close enough to 33" to me. Just as much as any other tire for that matter. Also I will be upgrading to 35's in the spring. 35 12.5 15 to be exact. Would love to know the true size of those. I've read somewhere its in the upper 34's. Would love to see proof though.

 

my KM2 35X12.5r15 are short, like 33 5/8 but they are great tires. True to size tires are Goodyear MTR K's, had them in 35 as well and they were a 34 1/2 on the jeep.

 

My opinion is the KM2s have a fairly soft sidewall, this softness causes more flex and "squish" that robs measured tire height. I have found that almost all tires measure very close to their advertised height when mounted to the suggested wheel width and are unmounted. It's the mounted height that varies. If you have a heavy rig you could see as much as 1.5" lost mounted VS unmounted.

 

I measured my 35x12.5x17 km2s the day I installed them because I had heard they can run a lot shorter. At 37 pounds the were 34.75. I was happy with that. I've since done the chalk test and am now running 29 PSI. I just checked and they measure 33.75 at 29 PSI while on the vehicle with 6K miles on them..

 

37 1250 17 km2 next to an Stt by Cooper. Granted the km2 is worn and the Cooper is new. But there was about a 2" difference in height l, mounted on the same wheel with no weight on it.

 

Wheel width will change tire height. A narrow wheel angles the sidewall which in turn reduces the height. I have 35X12.50X17 on 8" wide wheels on my JKUR and they measure at 33.5". I'm cool with it though because I wanted a tire that spec'd at 33-34" mounted.

 

Good point. My rims are 17x9 for comparison purposes.

 

So you lost about 1" after reducing the air pressure, 6K miles and adding the Jeep weight.

My tires on the Jeep squatted about 1/2". Wondering if your tires get any taller by going back to 37psi? If they increase 1/2" then that is comparable to mine.

And maybe the softer sidewall of the BFG is why it makes it such a good riding tire, and great off-road. At least IMO.

Now, if they weren't so damn expensive. I think lowest price I could find was $319 at 4wp.

 

Yeah the tread center was bowed out a lot with the 37 psi. I'm sure they would puff up again with increased pressure.