Larger tires on rear only

[SierraHDCC]

Other than the obvious speedometer-reading difference, does anyone know what the impact would be (if any) to install 285s on the rear and 265s on the front of a 2WD truck?

[Firetiger(MN)]

Other than the speedometer like you mentioned, on a 2WD I wouldn't see that there would be any other issues.

[SoMnDMAX]

The only reall issue I could see is with the antilock brakes. The system is calibrated for four equal size tires, and there's no telling how the system would work with two different sizes. It may be bad, it may not.

[Shaners]

The only reall issue I could see is with the antilock brakes. The system is calibrated for four equal size tires, and there's no telling how the system would work with two different sizes. It may be bad, it may not.

I agree that there could be an issue with the ABS...

[Guest]

Question: What is the need in the first place for new 265s in the front and new 285s in the rear???  ???

[MountaineerTom]

I may be wrong on this, so someone correct me if needed.  Some won't apply since it's going on your 2WD.

 

I've always been told it's not good to have two different size tires on the same drive axle (the rear on a 2wd, for example).  Reson being is that because of the different tire height, the two wheels will be rotating at different speeds, which would be hard on the interal parts.  For a 4WD, I would think the same would apply to the front and rear tires if you had 2 different sizes front to back and 4wd engaged.

 

But in your case (with 2wd), I don't think it would be a problem as far as what was mentioned above in my post.  The front tires would just be rotating at what ever speed the rear tires are pushing them.  Like mentioned before, you may have ABS issues though.  You could be in that situation above though, if you havd a flat on your 285's, and had to put the 265 spare on the rear.  As to how much actual damage it could do, I don't know.  It's just what I've always heard.  

 

Did any of that make sence?  ???

[Colorado Kid]

I don't know of any load range E 285's so you're talking about putting lighter construction tires, with taller sidewalls, on the back.  My dad once did this in an old C-10, running LT tires in front and passenger car snows (same size) in back.  It caused a strange tail-wagging sensation when you started to change lanes, due to the stiffer sidewalls on the front tires.  When he took it to a good alignment shop they told him that, and even swapped the wheels front to rear for demonstration.  Sure enough the wagging was gone.  Solution in this case was to buy two more passenger car tires for the front, to get through the winter.

 

If you run the same load range front and rear, and at least as much air pressure in the rear as in front you may not have the problem.  The ABS is a whole 'nuther can of worms, so I'll be keeping match sets of four on mine, but you do what you like with your's.

[chevyman16]

If you change your tires i believe it will screw up the transmission shifts. Your gas mileage will go way down because of this. Ive heard of guys who have had 2500's that came standard with 245's. They changed them to 265's and didnt get the computer changed. He experienced vibrations and really bad gas mileage. Since you would be changeing only the back tires i dont think you could change the computer. I would check in with your dealer or tire place to look into it. Just my .2

[gandolphxx]

With 2WD drive you can do anything you want to the rear axle as long as you reset the PCM to the proper values. In the case of 4WD, don't even think about different diameter tires front to back unless you enjoy replacing differentials.

[chevyman16]

With my above post...the guys who forgot to reprogram there computers....the trucks were 4WD. Im not sure it would have a big effect with a 2WD truck. Still check with your dealer.