Sooo, what damage will big tires do to the rig?

[semlin]

Dave, don't apologize. I have driven a 3FE a bit lately on 31 ATs head to head against my 93 with 31 ATs. There is nothing wrong with the power of a 3FE, and it handles great around town. It is much much closer than I expected to the 1fz. I'm with you and Landtank. In fact, given how cheap they are now, I think a 3FE 80 is a better deal than a 1FZ.

But I still prefer my 93

 

[xl715]

Landtank, No I'm not running factory rims. I run procomp xtreme alloys(imitation beadlock style) 16 by 10. I get alot of comments on these wheels, all positive. They really go well with the rig. If I can fiqure out how to shrink my pics enough I will post pics. BTW, still have my stock rims w/michelins at about 40%, Anyone wana buy them?

 

[e9999]

seems to me like just the larger weight of the bigger tire bouncing around is bound to increase stresses on the parts holding it in place (rods, bearings and all). Am a bit surprised that bearing failure was not mentioned more as a problem with bigger tires. Must be that these rigs are indeed well-built...
Eric

 

[landtank]

XL715, that's why you are rubbing. It has nothing to do with the tire size but more with your choice of going with a rim with the wrong backspacing. With the factory rims you would still need to adjust the stops but it would take quite a bit more than turning into the driveway to get them to rub. When I mean quite a bit I'm talking near full articulation. Now that I have re-sprung with the 850 OME I haven't rubbed at all.

 

[xl715]

Correct, landtank, however if you saw the stance of my rig with these rims you would definately agree that it is a needed width. As tall as my truck is I wanted the extra width. Now that I'm lifted enough I can fully articulate and not rub at all, and thats with a rear tire fully tucked into the fender.

 

[landtank]

It might help some of the guys, who are just getting into modding their trucks, to get a better explaination of your situation other than "they rub when turning in the driveway". Mentioning that "with aftermarket rims" they will rub when turning in the driveway, would help them better understand why I'm not having issues and you are. Not mentioning that could be confusing to a newb.

 

[xl715]

I would not run 35's with less then 5" of lift - it's just half assing it, and when you need the articulation off road you won't have it. You would be better to go with 33's and have more tuck then run 35's and rub!!!!

 

[landtank]

Well I'm happily half assing it and never intend to stop

 

[IdahoDoug]

Rick,

Yes while maneuvering there would be a bit more stress if there were lockers engaged, due to axle windup. But again, simply having larger tires on an 80 does not cause birf failures, I believe it is much more highly correlated to the type of use. In other words, I'd wager birf failures occur far more often on 80s that are used heavily offroad vs 80s that merely have larger tires. So, I agree that there are situations where an 80 with larger tires being used offroad can generate force spikes on the birfs that are higher than one with smaller tires, that's not my point. To the original question, I believe he was merely asking what damage would occur simply driving with larger tires and I contend none to the birfs. I agree with the previous poster that suspension bushings, shocks, brakes and steering components might have increased wear however. And I agree with you that larger tires AND heavy offroad use contributes to birf failures.

Generic,

What you are referring to is torque at the contact patch, which moves farther from the axle center with larger tires. The larger tire reduces torque at the contact patch due to simple geometry with the same engine power trying to move the car with a longer lever and attendent torque loss at the contact patch. But this does not change the amount of torque the birfield is receiving from the engine because that is simply a function of the engine's output. Interestingly this is exactly what causes increased brake wear, because the larger tires create a longer lever to resist the brake's attempt to stop the vehicle. It's a simple ratio - a 35" tire is approximately 10% larger in diameter than the stock tire and reduces brake capacity by 10%.

Overall, I have come out against larger tires for many years. I feel that they dramatically increase the danger of a roll on the road in exchange for an increase in offroad capability. A fine tradeoff for a trail rig, but questionable for one driven daily and used to carry family.

DougM

 

[xl715]

Hey, any cruiser is a good cruiser!! All written as info for others. Thanks for pointing out my non info post earlier!!!

 

[ginericLC]

Actually the math is not a simple 10% increase by going to 35s. There is a formula that can express how the increase in tire diameter increases forces, but I don't have it handy. It grows exponentially, it isn't a simple straight line for the growth. Increased braking distance for sure, more wear on the brakes for sure, I think the wheel bearing wear is very minimum. I realize that engine torque cannot be increased by the larger tires. But the increase in traction increases the torque applied to the birfield. Maybe this isn't important on highway driving? but I've never heard of a birfield snapping while driving down the interstate. Really maybe it isn't so much the size that breaks the birfield but the traction? I suppose a really sticky small tire could hook up really well and snap a birf too. I know that it does not have to be a spinning and then a hookup to break a birf. I've seen them pop with very little tire rotation in a high traction situation. I'm still sticking with my lever idea. The further out you get the adhesion the more leverage it applies.


I'm not concerned with the rollover factor of the larger tires on the road. I've increased my width as well with wider wheels with less backspacing. However on road handling has definitely been compromised, steering is good, brakes are adequate, there is a bit more body roll. And it is definitely louder running down the road. It is not to the point where I would not trust my wife to drive it or feel that my family is at risk. In my opinion, it handles much better than a lot of stock other SUVs. Expeditions are the ones that come to mind the most as our neighbors have one and I've spent some time it both driving and riding.

I'm running just J springs with no spacers and the only rubbing I get is on my rear mudflaps at full articulation with the 35s. After I trim them there will be no rubbing anywhere. So I don't think a 5" lift is necessary to not butcher it to get 35s. I think wheels are another way you can go with bigger tires without going up higher.

On my 94 I'm leaning towards a 33" or so tire. Not because I can't do a 35 but because I really don't think I need a 35. I can go with less lift and less height from the tires and still get down the trail. After loading a kid and dogs and gear into our 91 a few days I get real excited about loading stuff into our 94 which is stock. The tires are quite a bit cheaper too!