Need Opinions Please

Ganudorm · June 3, 2006

I just purchased a 1999 GMC Sierra Z71 a couple days ago and have been discussing options with my friends. I'm shooting to put 34s on it without them scrubbing but needed suggestions on what I should do to it. I do not want to spend alot of money on the actual lift but more on the tires and rims. A friend of mine suggested getting the torsion bars in the front tightened and blocks in the back, but another friend said that'd make the front of the truck bounc when you were going down the road. Another good friend of mine suggested I buy a leveling kit for the front and blocks in the back. I was thinking I might just invest in a 2" body lift but I would just like your opinions. Thanks!

Worktruck · June 3, 2006

The body lift is problably the best way to go if you have the time and money. I installed F**d keys in the front (do a search here on the board and you'll find lots of info) and Hellwig helper springs in the back. I got 3" of lift in the front and 2 1/2' in the rear. I think the truck rides better than befrore I lifted the front, too soft from the factory, but some people don't like the ride with the torsion keys cranked. Total cost for the keys and helper springs was about $120.00 Took about 2 hours to do the change out but the truck was fairly new at the time. Might take longer on an older truck with the rust and such. Good Luck let us know what you decide to do.

silveradoHO · June 3, 2006

I bought a leveling kit for my 05 silverado and the instructions said 33's were the largest tires I could put on. This is with the front lifted 3", so you will probably need to raise yours even more to put 34's on. You may need a leveling kit and a body lift.

snoman · June 3, 2006

Word of caution, 34's or 35 will shorten ball joint life and steering too on that old truck as the front end is not that strong and with 34's you will likley fry tranny (or shorten its life at the very least) if you do not regear it. as it will add a lot of strain to drive line anhd when they fail, people blame the tranny, never what they did to truck.

Deere_Daze · June 4, 2006

I dont think you will be able to go with 34s without some serious suspension mods.

I think you would need 2-3" of suspension lift with 2" of body lift to get the needed clearance for those tires.

Then you will need to regear, otherwise you truck will be gutless and you will most likely burn-up the tranny.

I dont think you will be able to fit 34s on your truck without spending a considerable amount of money.

Ganudorm · June 4, 2006

If I was to put 33s on it, through the technique the first reply said, would I have to regear it?

pm26 · June 4, 2006

If I was to put 33s on it, through the technique the first reply said, would I have to regear it?

<{POST_SNAPBACK}>

If the truck does not have 4.10 gears, do not even try bigger tires. You will lose torque and mileage big time. Bigger is not always better.

I actually replaced the stock 31X10.5R15 tires on my 95 Nissan 4X4 V6 pickup with P235-75R15 tires. My original gears had 4.23:1 ratio and the truck has a 5 speed manual with really low first two gears. After I switched to smaller tires, the off-road perfromance, and towing capability increased tremendously. The truck wotwed a 5000 lb trailer with ease (if would not go very fast with it but it did not seem to strain the crivetrain or the clutch). Had I gone to 33 tires instead (whichI have seen done on these little trucks) this thing would be worthless as far as torque goes. In fact, switching to smaller tires meant gaining 10% torque at the rear wheels, bigger tires would mean about 10% loss. At that is a lot in a small truck that only puts out 180 ft-lbs.

Same analogy applies to a Chevy Z 71.

snoman · June 4, 2006

If I was to put 33s on it, through the technique the first reply said, would I have to regear it?

<{POST_SNAPBACK}>

If the truck does not have 4.10 gears, do not even try bigger tires. You will lose torque and mileage big time. Bigger is not always better.

I actually replaced the stock 31X10.5R15 tires on my 95 Nissan 4X4 V6 pickup with P235-75R15 tires. My original gears had 4.23:1 ratio and the truck has a 5 speed manual with really low first two gears. After I switched to smaller tires, the off-road perfromance, and towing capability increased tremendously. The truck wotwed a 5000 lb trailer with ease (if would not go very fast with it but it did not seem to strain the crivetrain or the clutch). Had I gone to 33 tires instead (whichI have seen done on these little trucks) this thing would be worthless as far as torque goes. In fact, switching to smaller tires meant gaining 10% torque at the rear wheels, bigger tires would mean about 10% loss. At that is a lot in a small truck that only puts out 180 ft-lbs.

Same analogy applies to a Chevy Z 71.

<{POST_SNAPBACK}>

Nice observation. 4.10's would work with 33's but OD will not be of much use.

Worktruck · June 4, 2006

I have 265/75/16 BFG's on mine, that i believe equates to a 31-32" tire? I have 3.73 rear gear and have had no trouble to date.

snoman · June 4, 2006

I have 265/75/16 BFG's on mine, that i believe equates to a 31-32" tire? I have 3.73 rear gear and have had no trouble to date.

<{POST_SNAPBACK}>

Trouble is in the eye of the beholder because it will be lacking at times unless you are used to it. BTW, tire size is about 31.6 inch. If you go to link below you will find a tire size and axle ratio calculator.

Click Here

Ganudorm · June 4, 2006

If I was to put 33s on it, through the technique the first reply said, would I have to regear it?

<{POST_SNAPBACK}>

If the truck does not have 4.10 gears, do not even try bigger tires. You will lose torque and mileage big time. Bigger is not always better.

I actually replaced the stock 31X10.5R15 tires on my 95 Nissan 4X4 V6 pickup with P235-75R15 tires. My original gears had 4.23:1 ratio and the truck has a 5 speed manual with really low first two gears. After I switched to smaller tires, the off-road perfromance, and towing capability increased tremendously. The truck wotwed a 5000 lb trailer with ease (if would not go very fast with it but it did not seem to strain the crivetrain or the clutch). Had I gone to 33 tires instead (whichI have seen done on these little trucks) this thing would be worthless as far as torque goes. In fact, switching to smaller tires meant gaining 10% torque at the rear wheels, bigger tires would mean about 10% loss. At that is a lot in a small truck that only puts out 180 ft-lbs.

Same analogy applies to a Chevy Z 71.

<{POST_SNAPBACK}>

How would I check my gears? I want to be able to put atleast 33s on it.

silveradoHO · June 4, 2006

Check the RPO codes in the glovebox. One of them is for your rear axel

and should tell you your gears. Just write them down and do a search on this forum.

snoman · June 4, 2006

Check the RPO codes in the glovebox. One of them is for your rear axel
and should tell you your gears. Just write them down and do a search on this forum.

<{POST_SNAPBACK}>

GU6 is a 3.42, GT4 is a 3.73 and GT5 is a 4.10.

svensk · June 5, 2006

If I was to put 33s on it, through the technique the first reply said, would I have to regear it?

<{POST_SNAPBACK}>

If the truck does not have 4.10 gears, do not even try bigger tires. You will lose torque and mileage big time. Bigger is not always better.

I actually replaced the stock 31X10.5R15 tires on my 95 Nissan 4X4 V6 pickup with P235-75R15 tires. My original gears had 4.23:1 ratio and the truck has a 5 speed manual with really low first two gears. After I switched to smaller tires, the off-road perfromance, and towing capability increased tremendously. The truck wotwed a 5000 lb trailer with ease (if would not go very fast with it but it did not seem to strain the crivetrain or the clutch). Had I gone to 33 tires instead (whichI have seen done on these little trucks) this thing would be worthless as far as torque goes. In fact, switching to smaller tires meant gaining 10% torque at the rear wheels, bigger tires would mean about 10% loss. At that is a lot in a small truck that only puts out 180 ft-lbs.

Same analogy applies to a Chevy Z 71.

<{POST_SNAPBACK}>

How would I check my gears? I want to be able to put atleast 33s on it.

<{POST_SNAPBACK}>

You know I had some worthless 245/75/16 steeltex on my rig this winter and they rode and handled like complete crap so I got talked into 265/75/16 LTX/MS tires, and man does it ride better. But at what cost I guess now? My door sticker says my truck came with 245's with a 3.73 and I could constantly haze the tires leaving a stop sign or turning a corner with too much throttle. Now, I rarely spin the tires leaving a stop unless I completely gun it or its slippery. I don't tow much at all she is mainly just a daily driver, sometimes when I do it's my dad's 3,000lb boat which I don't even notice back there. I have no lift or anything just completely stock, would it even be worth regearing in my situation? I have been told that is kinda silly since I didn't upgrade my size that much.

silveradoHO · June 5, 2006

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You know I had some worthless 245/75/16 steeltex on my rig this winter and they rode and handled like complete crap so I got talked into 265/75/16 LTX/MS tires, and man does it ride better. But at what cost I guess now? My door sticker says my truck came with 245's with a 3.73 and I could constantly haze the tires leaving a stop sign or turning a corner with too much throttle. Now, I rarely spin the tires leaving a stop unless I completely gun it or its slippery. I don't tow much at all she is mainly just a daily driver, sometimes when I do it's my dad's 3,000lb boat which I don't even notice back there. I have no lift or anything just completely stock, would it even be worth regearing in my situation? I have been told that is kinda silly since I didn't upgrade my size that much.

<{POST_SNAPBACK}>

3.73 is a good setup for what you use your truck for. Your tire size now is the same as what a lot of 99-04 Z71's came with, and alot of those have a 3.42 ratio.

My 05 Z71 has 265/70/R17 tires and 3.42 gears, and I regularly tow 5000lbs with no problem. I would have liked to have gotten 3.73's, but they were not an option when I bought my truck.