I’m really glad to find this forum .i have a wrangler 275/55/20 all terrain with Kevlar I just bought and about to install. The guys at the shop kinda discouraged me and I wasn’t sure what they were saying but after going through the comments in this forum I’m convinced is ok.
another thing I want to ask is , apart from the Speedo is there any other issue(s) that may arise as a result. Thank you

 

I've heard that 31.5 is about as tall as you can go before you run into rubbing issues (front) at wheel lock. 275 55 R20 is 31.9" diameter. You might be able to mitigate that with some wheel spacers. I think there is slightly less height on the rear wheel wells and you might be getting close to rubbing the inside of the well at suspension compression. Come to think of it, are there any spacers you can mount on the air springs to increase stock ride height?

 

I've been thinking of going the opposite way down to a 265/50r20. This gives you way more tire choices. That is only 10mm difference down in diameter, 30.8 down to 30.4 which is just over 1%. Everything I have researched says you are okay if you stay with in 3% of original diameter. So I am guessing that is 1.5% up or down?

 

Should have added I am interested in All Weather tires. There are only 2 brands that make an all weather 275/50r20 Michelin and Toyo, but when I drop down to 265 there are other brand options. The cost to run summers and winters is getting cost prohibitive.
Bob

 

We put Michelin LTX 285/50/20 on my wife’s 2014 GL450. We were extremely happy with the tires & ride. These tires are a light truck tire and support the weight of the x166 very well. So much so that I bought a set of 20” factory wheels and am waiting until I need tires to put a set of LTX tires on my X166 (GL350 that came with 19” wheels).

 

So upon doing more research and finding a tire chart with tire spec's for all sizes I found that a 255/55r20 tire is 31", a 275/50r20 is 30.8 a minimal difference. The tire is good for 7"-9" rim width so it seems this size maybe a viable option.
Bob

 

Just to keep the Michelin defender LTX in the running the 285/50/20 has a diameter of 31.2”, no scrubbing on full lock turns.

 

I am leaning towards an all weather tire which are very limited in sizes and trying to stay close to the original size spec's, can be done on everything but I can get close. My son and his family moved to the interior of our province so I need something that is good for snow once in awhile.
Bob