What is the biggest tire I can put on a STOCK 98 Tahoe?

What is the biggest tire that I can put on my 100% stock 98 Tahoe?

I was thinking about lifting it, however because I do a huge amount of highway driving, i descided against it.

That being said, what size can I do?

I have had 285 BFG A/T ko's on my stock 99 for 45k miles and I have only seen a little rubbing on the sway bar and no damage to the tire, I drive on the freeway everyday and offroad about every other weekend . I know that 265 and 275 are the stock tires offered with tahoe. hope this helps
JD

JD's dead on. Any larger than a 285 (which translates to roughly 33 inches) and you'll get into problems rubbing the lower-rear portion of the wheel well during a moderate turns and suspension compression. This part of the wheel well, if you look closely, is of a odd double panel construction with a lip that sticks out. Part of this lip can be ground away very easily for a little extra clearance, and no one will be able to tell the difference. Grind any deeper and you're looking into some serious body work with that double panel--it has to be closed up because crap will slide in between those panels, down the body and rust out.

On the same note, you throw some larger tires on there and smash up that rear, double panel part of the wheel well, you're going to have to pay a body shop big $$ to repair that, and live with some undesired, "custom" tread patterns in your tire.

So I can safely say that i could put 275's on there with out any rubbing? rite now my stock tires are 245/75/16's, how much bigger will 275's be?

You should have no problems with those if you keep the stock rims. You could ask a tire dealer as well, but of course they're going to say yes b/c they want to sell you tires. If you want to figure out how large metric rated light truck tires are (in terms of inches), you can get into some math:

245/75/16 = section width(SW)/aspect ratio(AR)/wheel diameter (WD)

Tire Diameter in inches= 2 x (AR/100) x (SW/25.4) + WD

So your 245's are about 30.5 inches in diameter and the 275's you're looking at (assume same AR) are about 32.2 inches.

If i'm not mistaken 275's are a lot harder to find than 285's. Good luck with your search and really consider BFGoodrich's if you do go any bigger.

I have been noticing that, I'm thinking I'll go with the BFGoodrich Alterain AT KO's size 285/75/16's or 275/70/16's. I realy want to do the 285's, bc they are like 1.6in bigger. But I am realy worried about rubbing, because ontop of a large amount of HWY driving, I spend alot of time in the city trying to park. ;) Is there anything other than a lift i could do to my truck to make it so those tires wont rub?

You could crank your Torsion bars about an inch. That shouldn't effect ride much and will give you the clearance you want. I'm almost 100% sure 285's won't rub, however. I know many people with them on their 92-99 Tahoes and Blazers. In fact, I had the same query about a month ago and my research yielded that you could.

Ok, so another stupid Newbie Q. What are the torsion bars realy for, or rather what is their intended purpose?

The torsion bars replaced the need for springs in the front of the vehicle so instead of wound metal bar (spring) you have a straight bar that torques under load(torsion). least thats what I think.

JD

Here is a little piece on what a torsion bar is:


Torsion Bars
Torsion bar suspension uses the flexibility of a steel bar or tube, twisting lengthwise to provide spring action. Instead of the flexing action of a leaf spring, or the compressing-and-extending action of a coil spring, the torsion bar twists to exert resistance against up-and-down movement. Two rods of spring steel are used in this type of suspension. One end of the bar is fixed solidly to a part of the frame behind the wheel; the other is attached to the lower control arm. As the arm rises and falls with wheel movement, the bar twists and absorbs more of the road shocks before they can reach the body of the car. The bar untwists when the pressure is released, just like a spring rebounding after being compressed. Adjusting the torsion bars controls the height of the front end of the vehicle. The adjusting bolts are located at the torsion bar anchors in the front crossmember. The inner ends of the lower control arms are bolted to the crossmember and pivot through a bushing.

You crank that front torsion bar you're going to have a little rougher ride not to mention a "hot rod" setup with the front end up high (might look sort of cool, actually). Not to mention the bar sags back down over time and you have to keep cranking the bolts to raise it back up.

You can put new shackles in the back if need be, but the "hot rod" setup, as you call it, will not be noticeable.

well, given that i already have a bit of a saging rear end, and i meen on my tahoe. i may need to look into mabe a one inch lift or something.

Nice one, I had to pause for a second, but I got it.

I'm telling you, stay away from the block lift/torsion bar crank combos. It's a cheap/quick fix, but not only are you going to have a rougher ride and strung out shocks, you're going to run into problems with driveshaft geometry (new u-joint every few months, vibration, etc.) because those blocks have to be made perfect, and most aren't unless you get full lift kit from ProComp, Fabtech etc.. ($3k).

Body lift is definitely the way to go here. Doesn't change anything except the body height of the vehicle, adds a few gaps which you can fill, and you can even get it installed and everything for around $500.

Will a Body lift fix the problems being described (rubbing on sway bars)? I thought only a suspension lift would fix that, and apon further thinking I'm questioning whether it realy would?

You would need to get new rims and probably spacers to offset the wheels and keep them from rubbing. But I can do furhter research to make sure.

The tahoe does have leaf springs in the back? Correct me if I'm wrong somebody.

pick: yeah leaf springs
bartlanz: if your back is sagging a lift is not the anwser to the problem, you need to fix what is making it sag, unless you mean to replace the leafs then get the "lift" while your at it.

lifts will help with rubbing on the wheel well where the fender is, but the spacers are needed for rubbing when turning, inside the wheel wells.

as andjh123 said...

yeah if you dont know much about alignment stay away from your torsion bars, moving those will change your camber, and may requirme a professional allignment, but the amount of adjustment is minimal without changing the keys (octigonal mounts for the torsion bars).


as for spacers I think any increase in stress on an arm/bearing is a bad thing and the need for wider tires does not out wiegh the possibility of damage. 'course I still have not installed a lift yet, it really comes down to what you are going to use the tahoe for and what your willing to pay to keep it that way....

nobody has mentioned that if/when you change tire size (tread width) and don't compensate by reducing the aspect ratio (sidewall) so as to maintain the same tire diameter, you are going to render your speedometer useless (or at least render it innaccurate)

say you have stock tire size of 245/75-16 and you move up to a wider 265 tire, in order to maintain the same (very close to same) tire diameter, your aspect ratio needs to fall to a 70 versus the 75 of the 245 tire

basically, when you go to a wider tire, you need a shorter sidewall to maintain the diameter of the tire - this way you won't screw up your speedo calibration and you avoid the clearance problems of a bigger diameter tire, although you obviously need to be cognizant of how wide the tire is as far as clearance issues go

I know this is basic stuff, I just found it curious nothing was mentioned about this

If you had a 245-75-16 before and changed to a 285-75-16, it wouldn't matter. Am I correct in saying that?

If you had a 245-75-16 before and changed to a 285-75-16, it wouldn't matter. Am I correct in saying that?


no. it would matter.

in the 245/75-16, the sidewall height is 75% of the width of the tire

if you have a 285/75-16 size tire, then your sidewall will be 75% of 285 mm or exactly 30mm more than 75% of 245mm (although my calculator-less math may be off at this time of day, so you can double check ;)

therefore you will have a larger diameter tire and your speedometer will not be accurate

Ok, another thing I just noticed as I was looking at BFG's web site is that they say the 285's are for 7.5-8.5in rims, I only have 7in rims. will this be an issue?

I would bet the tire WILL fit onto your wheels, though they may appear slightly "fat" (for lack of a better term) due to the bead being pinched to a 7.0" wheel as opposed to the 7.5-8.0 recommended

So I submit that one could figure out exactly how much the speedometer is off based on the size of the tire (relative to the stock tires that it came with). Calculate change in circumference and then do something with that. It's too early in the a.m. and I'm still recovering from this weekend, so I'm not going to think about that for now.

And one more thing, could Bart's tahoe be considered a firetahoe? Or how about firehoe?

LOL, I was wondering how long it would be before that name was brough out. :lol:

My former vehicle was a Jeep Grand Cherokee, and it was well known localy, and around the Jeep comunity because of how decked out it was. It was commonly refered to as either the "Fire Jeep", or "a lightbar with a Jeep under it".

On the Tahoe I desceided to go just a bit more under cover, the only thing I need to finish it is a brush guard and two speakers for the siren. As time progresses you will see that picture change.

http://pages.prodigy.net/lblanz/FireJeep/@!.jpg

For more pictures of the Jeep: CLICK HERE (http://pages.prodigy.net/lblanz/FireJeep/)

So I submit that one could figure out exactly how much the speedometer is off based on the size of the tire (relative to the stock tires that it came with). Calculate change in circumference and then do something with that. It's too early in the a.m. and I'm still recovering from this weekend, so I'm not going to think about that for now.

I did the math a while back for this and I found that the differential when you upgrade from 245/75/16 to 285/75/16 the gauge is off by 4mph each 50mph, so when it read 100mph, I was actually traveling at 108mph. I'll look for the formula but i think there are a couple online.

JD68

Yeah I get [a little] satisfaction out of figuring (or at least trying to) that sort of stuff out. After over-analyzing the problem (like I do for most things) I came up with a bunch of formulas and other various chicken scratch. Then I went on the internet calculators because I don't trust myself....

Bottom line: it looks as though you get about +/- 1.8-2 mph error in speedometer per inch of tire diameter change.

So I could see some significant change to bigger tires (with no speedo adjustment) causing problems with the cops. However, if you speed like a madman in the first place then don't even worry about it!

LOL, I tend to "speed like a mad man". But I don't get pulled over too often. :lol: :wink: I'm just guessing here, but I think it has to do with the square red thing ontop of my Tahoe :wink:

Just go with 285s

LOL, I tend to "speed like a mad man". But I don't get pulled over too often. :lol: :wink: I'm just guessing here, but I think it has to do with the square red thing ontop of my Tahoe :wink:

Hmm...I've been bugging my mom for many years now to hook me up with some of those license plates the state gives to court judges...I hear those do the job nicely as well.

oh yeah, for you guys bent on going to a taller tire/larger diameter and wider tire (as opposed to a just wider tire with shorter sidewall to maintain the same tire diameter) - when you move to a larger diameter tire, you are going to lose some acceleration, esp. at lower speeds/standstill (although, if your engine has the power, you will have a higher maximum MPH) due to the tires playing an important role in final drive ratio, along with most importantly your ring and pinion gears (ie: 3.73:1, 4.11:1, etc)

This is true, significantly larger tires can require a new rear end with a higher ratio. However, small increases in diameter actually serve to increase highway gas mileage to an extent.

Just thought I'de let You guys know I ended up going with 265/75R16 BFGoodrich Allterain T/A KO's THEY RIDE REALY NICE

pics?

I have not read through all the posts, so I do not know if this has been mentioned, however if you go to a larger tire, you will have to make a tire diameter change in the PCM to correct the speedometer, for the PCM uses the MAF readings AND the speedometer readings to shift the automatic transmission.