Biggest Tire Possible on Stock Suspension and Setup

[Seger]

I have a 1998 Chevrolet K1500 Z71 Extended Cab Fleetside. I was wondering what would be the biggest tire combinations I could put on my truck currently with a completely stock suspension set up and not having to do any modifications at all? Also what are the best All Terrain tires for the money for the OBS? I want the best value in other words. I have not cranked the torsion keys either, as they are completely stock. I currently have 265/75r16 with the stock rims on goodyear wrangler armortrac's. I want something that will give my truck a little bit more increase in height as well as a little bit more width on the tires so they stick out a little bit without messing with the torsion keys or lifting any. Also, I want to make sure that I don't have to regear my front and rear diff. I currently have a 3.42 final drive ratio. Any suggestions would be greatly appreciated.

 

[slowburb]

You have a 3.42 gearset. Your final drive ratio is calculated using the gearset ratio, transmission final drive ratio, and tire height. With a 3.42 gear, I'd be extremely leary of increasing tire height because it will effectively decrease all of your drive ratios to unfavorable figures, which will adversely affect performance and powertrain loading.

All that said, you could probably slip a 285/70/16 in there without having to increase preload on the torsion bars.

 

[Seger]

Thanks for the quick response slowburb. If I were to increase my tire size combination to a 285/70/16 will I have to change the gearset? Also, how much will my speedometer be off from the actual speed if any?

 

[Biggershaft96]

Thanks for the quick response slowburb. If I were to increase my tire size combination to a 285/70/16 will I have to change the gearset? Also, how much will my speedometer be off from the actual speed if any?

I run 285s with 3.42 gears and it does just fine. Ive never had any other size on the truck but i doubt itll be that noticable of a difference power wise. when my speedo says im doin 60 im really doing about 66mph according to the Noble county sheriffs dpt lmao. Im assuming its calibrated for 245s though because thats what the door sticker says.

 

[slowburb]

Play with this. http://tri-5.chevyrides.com/rpm.php

 

[Seger]

Biggershaft96 what kind of tires are you running? What are the best All Terrain Tires with that size?

 

[Biggershaft96]

I have mastercraft courser mxts. The best all terrain is just a matter of personal preference and what fits your needs. For instance: winters can get pretty hairy around here so when i pick out a tire it has to do good in the snow. Treadwear doesnt mean very much to me because my truck sits the majority of the time and i only live a half mile from work. So if it only lasts 20,000 miles im happy because thats like 5 years of driving for me. Also this is my second set of mxts on my truck and theyve been excellent in the snow.
My personal preference for all terrains are probably the old style bfg all terrains. The new style has the 3 peak mountain snow flake symbol and theyre supposedly better in the snow so that would probably be my choice if i had to have an all terrain.

 

[slowburb]

You won't "have to" change gears to run 285's, but you may want to when your truck has a hard time getting out of its own way. The Cooper Discoverer AT3 is a great all terrain, possibly the best out there with regard to durability, treadwear, on/off road traction, and price.

 

[white_trash88]

I ran 35/12.5/15 with full crank and minor trimming to the bumper no rub on my 88. It had OK power. Would I do it again? Hell no. I'd run 285/75/16 with no crank or minor cranking. BTW I also have 3.42

 

[df2x4]

I ran 285/75/16s on my Suburban for a couple years with no rubbing issues at stock height. It has 3.73s, though. Like everyone else is saying, I'd be cautious about increasing tire size with 3.42s. You may not like the power loss.