2012 Jeep Wrangler Sport: New Wheels and Tires
December 20, 2011
Our 2012 Jeep Wrangler has new shoes. Man, what a difference. In no time at all we've gained about 2 inches of ground clearance owing to the larger radius of these tires. And the dorky mail truck look is long gone.
We of course mounted the BFGoodrich KM2s white letters out, in accordance with IL reader poll results. Frankly, I like it better than I thought I would. We'd have had too much black otherwise.
Of course gearing has suffered. And the speedometer is now off by about 10 mph at freeway speeds -- the wrong way. It read 60 this morning when I was going about 70 mph. New axle ratios are in the cards, but we're going to live with this awhile and measure the ill effects at the track.
On the road, acceleration isn't near as bad as I expected. Maybe that's because the 3.6-liter engine packs 83 horsepower more than the 2011 edition, has 23 lb-ft more torque. It also has a 6-speed manual, which means the gears were never canyons apart to begin with. With these tires it feels pretty natural if I ignore 6th alltogether and drive it like a 5-speed.
Yeah, there's more tread noise, but not as much as I expected and it's not that evident until 40 mph. Our soft top isn't helping, of course. Braking doesn't seem too bad in normal use, either.
We'll quantify all of this when we take it to the track next week. Should be interesting.
But you wanted to know how much these babies weigh...
That's right, each wheel and tire assembly weighs 91.4 pounds, exactly 40 pounds more than the originals. According to Price is Right rules, aspade called it with a guess of 90 pounds.
And so our Wrangler gained 200 pounds in one go; 40 pounds of pure unsprung weight per corner and another 40 for the spare. The ride is a bit more "clompy" over rough stuff at speed, but it's not a dramatic change because the Wrangler's solid axles didn't exactly represent a Lexus starting point.
Upgraded shocks will help and we're just beginning to play with air pressure. With a higher rated load capacity, we can safely run these tires at a slightly lower pressure than stock if we so desire.
In corners the extra tire footprint and the increased track width seem to make it feel more planted despite the extra height. The track is about 4 inches wider at the center of the tread and something like 6 inches wider from outside rib to outside rib. (We'll measure these numbers later.)
At just over 50 pounds, the old rubber came off rather easily.
But I was glad to have a Go-Jack roller jack handy to save my back the hassle of lifting a 91.4-pound replacement into place while the Jeep itself was suspended at knee height by our Rotary lift. Here the tire sits on rollers that allows me to clock it into position and line up the studs. These jacks are usually used four at a time to move cars around in tight spaces, but we've figured out a couple of other ways to make them pay for themselves.
Dan Edmunds, Director of Vehicle Testing @ 6,155 miles
Photos by Scott Jacobs