LibertyGuy wrote:
1. Is there any slight increase in fuel consumpion due to the bigger size compared to the stock?
2. Does your speedometer screw up in any way because of the bigger sidewall?
3. Does the vehicle bounce around more and not as stable because of the higher sidewall?
Thanks for the help!
I'll answer your questions based on my '03 KJ Sport w/245/70R16 (29.5" diameter).
1. Probably, but negligible -- I'm
guessing 1 mpg, but I drive conservatively. Plus, since my speedometer/odomter is off by two hairs, my mileage calculations aren't entirely accurate. With gas costing $2.55/gallon, I can't afford to have a heavy foot. The original 17/21 mpg wasn't very good to begin with, so I don't have a problem with losing 1-2 mpg from my daily driver. The improved handling and safety makes it worthwhile. The original 215/75R16 stock tires frequently lost traction on wet pavement. Although they had plenty of tread left at 39K miles, I replaced them out of concern for my family's safety and the need for a tire with a more aggressive tread for off-pavement driving.
2. Any time you put on a taller tire than what came from the factory, you cause your speedometer and odometer to be less than 100 percent accurate. From what I've been told and read, the deviation is only about 1.5 mph when travelling at 60. So if I'm really travelling 62 mph while my speedometer reads 60, I can live with that. It won't be the difference between a speeding ticket and no speeding ticket, if that's your concern. I've had my vehicle serviced at my dealer several times since upsizing tires, and no one has so much as commented on it. If you want an accurate speedometer, you can pay a dealership ~$100 to recalibrate yours, or by one of the inline digital converters for ~$179. (The latter would be helpful if running multiple sets of tires like a smaller, lighter set for the road and a beefier set for mud.) I have an 18.5-gallon gas tank. I rarely get 16.5 gallons in when filling up from "empty." My trip odometer currently reads 140 miles with my gas tank half full (mixed city & suburband driving). I typically fill up every 265 miles, right before my fuel gauge needle is actually resting on the Empty pin. Based on the 18.5 gal. fuel tank, I could probably drive another 30 miles, but I don't want to risk running out.
3. To the contrary, my vehicle felt much more firmly planted on the ground after installing bigger/wider tires. The increased tread width and better tread (compared to Goodyear Wrangler ST's) gives a wider stance that helps to counteract body roll in turns. (I lost a little bit of that by installing a lift kit, but body roll is no worse than stock. From what I understand of physics, the wider track and lift have cancelled each other out.) I run my Generals at 30 psi, and the ride on the road is nice. I won't go lower, especially when carrying a full load. I used to fill them to 35 psi, but I didn't notice any improvment in mileage, and the ride was too rough.
I hope this helps.
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