^ I switched my Suburban back to stock 245/75/16s for exactly those reasons. The 285s I had came on a different set of wheels that I was using for a while. Speedometer ran a little bit slow, but only by a few MPH. I'd imagine it threw my odometer off a little bit, too. I will say though, it handled the extra rubber just fine as far as power with the stock 3.73 gears.
Worth mentioning that if you care about this stuff, you can always have your PCM tuned by someone like Black Bear Performance. They can correct your speedometer/odometer for non-factory size tires. If you ask me we Vortec guys are lucky, I'd much rather swap a PCM out than mess with soldering on a DRAC personally. To be fair the DRAC solution for TBI trucks is a lot cheaper than a tune, though.
and changing a gear on a carbed truck is easier and cheaper yet.......
as some know i live in NYC and when i'm stuck driving in the stead of riding it's usually bumper to bumper traffic....so getting the rig moving is important.....as is passing all the alien monkeys that "drive" around here. if my stock L31 didn't **** the bed i would have wanted 3.73's for the bottom end torque........the flip side of this is my long trips with the truck......fuel economy (did i just actually type that?) is somewhat a factor.....considering i'd rather get 15 as opposed to 12.
after the stocker blew i swapped in a GM HT383E....there were no more power issues to consider...so 73 mph rpm's were then a consideration.......have to trade something to get something.......i decided that the 3.42's she had was a perfect(and cheap) compromise for how i use the truck with the tire size i have..........fuel economy actually went up after the swap and i have all the power i'll ever need..........yea, i'm still going to have it dyno tuned with all the other modifications i did, but this setup is perfect for ME.
in the past all i've ever had was 2nd gen K/5's....and 33" with 4.10's or 35" with 4.56's were perfect....especially on the overdrive trucks. my '85 Jimmy with the 305 consistently got 21 mpg with 35's on the road......i never lifted them over 3" either.......the lower they are the less drag they make and remain stable. articulation was never an issue with strategic trimming of the front fenders either.
as to the author of this thread, i concur.......go with the 285's. i don't see it affecting things too much if it's not your daily driver.