Posted this on Rubicon Owners Forum, but thought y'all would be interested also.
Due to an accident, I recently had to replace my Goodyear SilentArmor tires. I really like the tires, great traction, great wear, and quiet as the name suggests. But, I had been reading a lot about tall tires (pizza cutters) and decided to go skinny. Unfortunately, except for Interco, there aren't any DOT approved options.
I was running 265/85-16, load range E. According to Goodyear, 31.7 inches diameter. It just so happens Goodyear SilentArmor, 235/85-16, load range E had a listed diameter of 31.7 inches also. Exactly the same tire except for width. My scientific curiosity took over and I ordered 4.
The ride is much smoother. Probably due to lighter weight and fresh, deep tread. Also, it feels like I have ram assist on the power steering, less scrub from a narrower tire, it is much improved. Traction seems the same, actually very good.
This blew me away. I love tracking my mileage, even have an iPod app for it.
Mileage before, 265's, averaged about 16.1. Not too shabby for a 4.6 stroker. New 235's, for 4 tanks, was 17.1, 17.8, 20.1, and 18.2.
Now, that's 16.1 to 18.3 mpg from a 30mm tire width change, same 31.7 diameter (not counting wear on older 265's!). That's a 13.7% increase.
Sum it up:
Why didn't someone tell me about this sooner?