I have a '98 Ram 1500 4x4 and want to put 285/75/16's on it. Has any one done this and are there any negative effects like shift points changed, overdrive messed up, or does it cause vibration problems? I know the bigger tire will affect the speedometer but will I see a drop in MPG? Thanks

 

I do not have 285's but am planning on getting some. From what i understand there will most likely be NO rubbing, however depending on tread type "maybe worn out shocks and/or springs" you may experiance a small amount of rub at full turn. However for about 100$ you can buy 2" spacer"leveling kit" and that will elminate all rubbing problems. I have yet to find anything about effects on shift point or overdrive so i would have to say no. Same with vibrations however depending on the tire road noise may increase. MPG should not be affected much as long as same driving habits are kept. The truck may seem a little sluggish but nothing justifying re-gearing or HP upgrades excpecialy if you have a 5.9L. I think the speedo is about 5mph slow at 50 meaning when it shows 50 its closer to 55.None of this is 1st hand experiance so you may want to get "primary" sources before making any decsions.

 

i have 285's they rub at full turn very littel. The speedo is about 5 off and the mileage is about 1 or 2 mpg worse but they look cool

 

What is this- 'about 100$ you can buy 2" spacer"leveling kit" and that will elminate all rubbing problems'

 

Also depends on what wheels you have. If you're using stock wheels, there will be little to no rubbing. If you have aftermarket wheels with less backspacing, you will have considerable rubbing. I've got a '97 Ram 2500 with 285/75r16's on aftermarket aluminum wheels. The 2500 sits 2-1/2" to 3" taller than the 1500, and I have considerable rubbing on my nerf bars and mud flaps at full turn. On stock wheels it wouldn't have been a problem.

 

The pic in my sig is mine with 285's. Speedo is 2.4 mph off as GPS verified. That works out to one line on the speedo. So if you want to do 45, do one line under 45 and your good.
Haven't noticed anything bad, I do get a little better mileage on the highway with the taller tires. Size isn't that big to really change much with a 360.

 

Thanks for the replys guys-
I do have the stock rims on the truck and it does have the 5.9L. I bought a set of Bridgestone Dueller Revo's for it and I'll take a 1-2 MPG loss for the awesome look. The wheelwells look to empty with the 265's in them.

 

Just curious how do you guys find out what size diameter the tires are as when they say 265/75/16 I know 16" is the rim size but how do you find out if it is a 31" tire or 32" or whatever size it is. As for the rubbing I don't know I have bigger tires than that on aftermarket wheels but also have a 3 inch lift and at full turn the may rub a tiny bit but not much it is close though.

 

I am running no lift and have no rubbing. Its been wheeled hard too. Here's some more pics.



This pic I wanted to see how it flexed, and the tires still didn't rub.




As for the tire size, do a search online for metric tire size conversion and there's a lot that will come up.

 

You can also get something like Hypertech II or Jet performance has a transmission chip that will allow you to tell the computer what size tires you have and will adjust everything for you , like your speedo and shifting points.