bigger tires

[CCRanch]

talking to Discount tires about going to 285 tires from stock 245. He said I would have to re-program for the Allison to read the correct speed on the speedometer. Is he correct. Also, what kind of programmer do I need, or is it too much trouble, and can it void my warranty. I have 4000 miles on my 06 2500HD 4x4. I see alot of trucks with the 285-75-R16 tires and wonder if they all re-programmed. Thanks for any info.

[DmaxMaverick]

Most folks just upsize, and live with an inaccurate speedo/odo. The upside is your warranty will last longer (less miles racked up per actual). The downside is, of course, not being accurate, and the problem the dealer might have with it. I have 285's on, and correct the speedo/odo with a Predator programmer. The dealer can't/won't reprogram for larger tires. They can/may reprogram the PCM for ABS function, but that won't correct the speedo/odo. The programmers that will do it are Predator, Hypertech, Superchips, and maybe a couple others that don't come to mind right now.

My dealer doesn't have a problem with the larger tires I have, which is not typical of all dealers. They did ask if I calibrated my speedo/odo, and verified it.

[upsguy]

Would larger tires affect gas mileage. When I had a dodge gasser, I went from 245's to 265's and didn't notice a difference, but from 245's to 285's is a pretty big jump. I was just wondering. I'd like to put some bigger tires on mine too. Those 245's look kinda wimpy.

[FBJR]

Most of the handhelp programmers will let you set the tire size. You can add power or not. It will let the brakes work correct too which many don't think about.

You can also use them to check for codes and such. They go for around $300 and you it forever.

I am using the Diablo which lets you adjust alot and can be upgraded over the internet :D

FB

[cwood]

I had an 04 LB7 with 285's and didnt reprogram anything had no problems just knew spedo was off. Just bought an 06 LBZ and had the dealer put my 285's on new truck after they switched them they told me that they would void the warranty. they said that 275's and smaller were fine.

[Melvin P. Thorpe]

My tire dealer said that for them to put 285's on my truck I needed to change out the rims to 7" from the stock 6 1/2" rims. They told me they had all kinds of trouble with the larger tires on smaller rims. Just bull or true?

[Quack_Addict]

It's not even worth considering, in my opinion, changing from 6.5" rims to 7". The stock tires 245 tires are 3.1" wider than the stock 6.5" rims... technically, to keep the same tread width to rim width ratio, you would want at least 8" wide rims for the 285's.

I ran 285/75/R16 Michelin's on stock rims on my 2002 HD for several years and never had any problems - tire wear was pretty even (no bare patch down the center). I think I ran 50psi in the tires but don't remember for sure now.

I think GM has more of an issue with the load range of the 285 tires vs. what the truck is capable of. You can't get a 285/75/R16 with the same load rating as the stock 245's (that I know of anyway)... it doesn't mean much if you carry or pull light loads but if you load up to GVWR it's a different story.

[DmaxMaverick]

....I think GM has more of an issue with the load range of the 285 tires vs. what the truck is capable of. You can't get a 285/75/R16 with the same load rating as the stock 245's (that I know of anyway)... it doesn't mean much if you carry or pull light loads but if you load up to GVWR it's a different story.

True, in a way. The stock 245E's are rated at 3042#. The 285D's are rated at 3305#. The problem isn't the capacity. GM has a problem with the size, and has issued a bulletin instructing dealers to deny acceptance of a warranty complaint for powertrain issues if the tire size is anything other them OEM. I've been running 285's for near 100K on 16X8 Centerline wheels, and much towing near/at GCWR. Very pleased with them.

[cwood]

My dealership told me last week that 275 and smaller were fine, and to put smaller tires on before bringing it in for powertrain problems if running 285's or bigger. I recently moved and my old dealership put 285's on my last truck for me and never said a thing. I love my chevy truck but am getting tired of all the stupid little rules they come up with.

[FBJR]

They sell them with factory tires bigger than that!

Plus what about when they lift a truck?

Running 295/70-17s and love em :D

FB

[Melvin P. Thorpe]

DmaxMaverick, have you had any rubbing problems with the 8" rims and the 285 tires? I like getting the extra load capacity and a better looking tire/rim combo.

[DmaxMaverick]

DmaxMaverick, have you had any rubbing problems with the 8" rims and the 285 tires? I like getting the extra load capacity and a better looking tire/rim combo.

Initially, yes, at turning extremes. Slight rubbing on the passenger side at the air dam and the front and rear of the fender liner. I removed the air dam, but you can trim it to clear. I also cranked up the torsion bars to get the truck near level. I used a heat gun to "reshape" the fender liner, and "tied" the liner in place with wire ties. Now, the wire ties aren't necessary, as the liner is holding the shape permanently. Rubbing on the driver's side was only at the air dam and very slight at the front of the fender liner, but the reshaping took care of that. My truck looks good with the air dam removed, but not all models are the same. I think the Chevy, and later GMC don't look as good with the air dam removed. There's some pic's of the truck in my sig.

The rubbing issues I've had with 285's (or larger) have been very typical. You should expect the same thing.