I need to replace my tires bad, I already have my new 285s, however; I don't have time to get my Skyjacker springs on for another couple of weeks, and my truck desperately needs the tires yesterday! I was just wondering if there will be any clearance issues, and if I will be ok to run the 285s for a couple of weeks until I can get the springs on.
Thank you.

 

When you are refering to stock suspension, are you talking about the bagged out factory springs?

My truck (as you can see in my signature) has the factory bagged springs on it without clearance issue. It is close, real close. I am rubbing off a bit of paint every once in a while. I am running after factory aluminum rims(16x8).

 

I don't know what you mean by bagged out, its just stock leafs. I will be running them on a set of M/T Classic II's.
Thanks

 

Bagged out meaning sagging from the weight of the cummins sitting on them for over a decade. I'm running 255/85R16s which are about .5" taller/ 1" narrower than 285/75s and I don't think I could get them to rub if I tried.

 

gotcha.
Thanks guys.

 

Do you have the rubber trim around front wheel wells? I ran 285's on stock wheels for a while and had minor rubbing on drag link then with 2 1/2 skyjackers and new 16x8 wheels would rub on molding when turning and going over bumps.

 

What brand of tire are you running? I really want to run a set of those, but the only style I can find is BFG Mud terrains.

 

Toyo makes the 255/75R16 too. Either in M-55 model or Open Country for sure. I just put a set of Toyo Open Country MT 285/75R16, I have yet to take pics but will post. Love them so far, no rub at all.

 

Not to hijack, but anyone who has changed directly from the 235/85 to the 285/75, what kind of mileage difference have you seen? Thanks,

-Steve

 

I went from 245 to 285 about 2000 miles ago.

Before with the cruise set at 65 I was running between 18-1900 rpm. Now I run between 15-1600 with the 285's. Its got to help some. Don't forget to all an additional 9.5%????? to your miles traveled to get the correct MPG.

My GPS shows just shy of 10% slower on the odometer than my actual speed.

TallTom

 

Thanks. What I am curious about, is does the lower RPM's make up for the increased frontal area of the larger tires? As it is, with stock sized tires my speedo is already about 6% off on high side, so I expect it to be not too far off with the larger tires. But yeah, I check with GPS miles traveled.

 

I have not had the tires long enough for a good test. I also put on a Max Mileage chip the day before the tires so I may never know for sure.

It sure makes my truck look better with the bigger tires.

Tom

 

Steve I just changed mine from stock about 1.5 months ago and have been testing the mileage. I don't have an RPM gauge, but I found the opposite of TallTom. Just listening to the sound of the truck, I would say the RPMs have increased to reach the same cruising speed with the stock tires(which, to me, make sense as the truck is using some additional HP to turn that wider, taller tire,especially a mud terrain). My results so far show a drop in MPG by 1.5-2 MPG turning the big tires, but I beleive it's still too early to draw conclusive results.

Something I can't explain, I took my GPS in the truck with me with these new tires and the odometer was bang on with the GPS reading?? Which makes me question if my stockers were reading correct. I'm almost tempted to throw the old rims and tires on just to try, but I'm getting lazier as I age.

 

Thanks for the info. That is what I am curious about. I know the previous owner had the 285/75s and he said the speedo was pretty much on. I don't think there is anyway that your RPM's have increased, but maybe there is more load on the engine pulling the larger tires. Your odo reading wrong before may be why you are seeing a mileage drop, when in reality it hasn't.

 

Assuming your clutch is not slipping, that's not possible. The gear ratios and tire circumference are not variable. A taller tire has a larger circumference which will lower your RPM for any given speed. This cannot be changed.