Hi, My name is Ron, I have a question about truck tires. I own a 1988 GMC full size 4 wheel drive pick-up. I want to put bigger tires than original on it. I want to keep the 16 inch wheels that are on it now. Question to put 285/75r16's on it. Does anybody see a problem with that? Will they rub on a turn? Will they effect my speedometer reading?Will they have any effect on my abs?Will they effect my on board computer?Thanks, Ron

I don't know what size tires you have on there now but that tire size doesn't sound too much different. They should work OK with ABS if all the tires are the same size and manufacturer. Again depending on how much size change there will be, the speedo may be affected slightly but probably not significantly. The on-board computer (ECM or EBCM) shouldn't be affected. If all the tires have the same rolling diameter, the vehicle speed will be even but slightly higher.
Many people don't realize the affects on other systems within the vehicle: due to larger tires, being heavier, and having a larger rolling diameter, you change the overall gear ratio, calculated from the engine through the trans, out the drive axles and to the road. You may feel as if you've lost some power/acceleration. Also affected, slightly, is braking effort. Braking distances will be slightly greater.
Don't get too worried. These changes will only be as noticeable as the difference in tire size.
Clear as mud?

Normally, I'm not a fan for installing oversize tires. There can be a host of unexpected consequences--ranging from safety issues to premature wheel bearing failure. If you are involved in an accident and someone gets seriously injured or killed, personal injury attorneys can argue gross negligence. PI attorneys even challenge ABS algorithms in serious accidents.