35's or 37's ?

[VanCityRob]

Hey guys,
Just installed a 6" zone lift and now have the option of getting some bigger tires. I would like to get 37's but I don't want to harm my truck by putting tires that are to big on it.anyone know of a reason why I shouldn't go for 37s On a 17" rim?

 

[brandonjansen]

3 questions:

1) What is your exact lift setup? Just a Zone 6" lift or did you add Bilsteins?
2) What are your wheel specs? (width, offset)
3) What gears do you have?

 

[VanCityRob]

Just a zone 6" lift with a 3" rear coil.tires are stock size just on a 17" rim with 2" wheel spacers. I'm looking at getting 37 12.50 17 toyo open country M/T with an off set that is just a bit greater than a 2" wheel spacers.

 

[crash_eco]

Just a zone 6" lift with a 3" rear coil.tires are stock size just on a 17" rim with 2" wheel spacers. I'm looking at getting 37 12.50 17 toyo open country M/T with an off set that is just a bit greater than a 2" wheel spacers.

i have nothing to add other than, those are awesome tires.

 

[Revo]

Just a zone 6" lift with a 3" rear coil.tires are stock size just on a 17" rim with 2" wheel spacers. I'm looking at getting 37 12.50 17 toyo open country M/T with an off set that is just a bit greater than a 2" wheel spacers.

You'll likely rub on your front valence w/ 37s (I did, just had to trim a bit). What about your gears?

 

[VanCityRob]

Gears are stock. I had heard of people changing them. Should I? If they rub I don't mind trimming

 

[R/T_Fire]

Gears are stock. I had heard of people changing them. Should I? If they rub I don't mind trimming

If they are 3:21's, I would with 37's. I believe 3:92's are the largest gear that is produced for the front diff, so that will limit you selection. I'm sure someone will correct me if I am wrong.

But the High gear ratio will be sluggish due to the tire size. a Lower gear ration will rebalance the relationship between tire size and gear ratio so its not so slugglish.

 

[SuthrnRAM]

If they are 3:21's, I would with 37's. I believe 3:92's are the largest gear that is produced for the front diff, so that will limit you selection. I'm sure someone will correct me if I am wrong.

But the High gear ratio will be sluggish due to the tire size. a Lower gear ration will rebalance the relationship between tire size and gear ratio so its not so slugglish.

I would think the 3.92s would be better suited with the 37s vs the 3.21s. Or if you could upgrade to like 4.88s probably would be even better I would imagine.

 

[brandonjansen]

Just a zone 6" lift with a 3" rear coil.tires are stock size just on a 17" rim with 2" wheel spacers. I'm looking at getting 37 12.50 17 toyo open country M/T with an off set that is just a bit greater than a 2" wheel spacers.

You won't fit 37's on that lift setup with that wide of a stance without a fair amount of trimming. If you want to avoid that you'll be looking at a narrower stance or more lift.

If they are 3:21's, I would with 37's. I believe 3:92's are the largest gear that is produced for the front diff, so that will limit you selection. I'm sure someone will correct me if I am wrong.

But the High gear ratio will be sluggish due to the tire size. a Lower gear ration will rebalance the relationship between tire size and gear ratio so its not so slugglish.

3.92's are the lowest gears you can get from the factory. You can run lower gears but it will be aftermarket parts and the front diff will require machining to make them fit.

I would think the 3.92s would be better suited with the 37s vs the 3.21s. Or if you could upgrade to like 4.88s probably would be even better I would imagine.

4.88's would be a little much for 37's. 4.56's are the best ratio for them.

 

[VanCityRob]

this may sound like a stupid question but am I going to wreck anything if I don't change the ratio?

 

[R.L.K.]

You will not " wreck " anything .
Do you know you definitely have 3.21 gears ?
You may have 3.55 or 3.92 .
Do you have a 6 speed xsmn or 8 speed ?

 

[R.L.K.]

Oops , sorry I just looked @ your profile 2012 ...

 

[R.L.K.]

Regardless of what gears you have 3.21 , 3.55 or 3.92 , you will be fine , better with the lower gear ratio of 3.92 .
3.21 will just not be as peppy , 3.55 obviously would be mid amount of git up & go.
It's a 4x4 with a 6" suspension lift and 37" tires , it will look great and perform well on and off road .

If you want Viper acceleration then you would've bought a Viper .

Bottom line you'll be fine , drive it normal and perform regular , preventative maint . and use your head based on the added stresses your lift and tires are putting on your drivetrain.

Remember the good ol'days 50+ less HP and weak xsmn's and most didn't know or understand what gear ratio was ..... yep I do back in the 70s &80s and 90s .
We still drove our trucks everyday .

I agree with the above-mentioned, you will rub with that wide stance . Either go with a 1" spacer , diff wheel offset or install a 3" body lift .

 

[Revo]

I will chime in and say this: 37s and 3.21 gears is NOT a fun combination by any means (with an 8 speed). I lasted about a month before I couldn't take it anymore. To answer your question on the topic of wrecking anything w/ 37s and high[er] gears, instantly? No. Over time? Yes, due to the amount of additional stress put on the engine/transmission.

 

[BOWERSFJ]

Opinion time . . . 6"F/3"R lift with no additional lift (Bilsteins/Body) and 37" tires is going to look stuffed . . . I think your best bet is 35's . . . Then again, maybe that's the look you want . . . I don't see many 6" lift guys on here going with the 3" rear option, so it may be tough to find any example pics . . . And I have to agree with Revo, unless you have 3.92's, I wouldn't even think about 37's . . . I have the Zone 4" with Bilsteins and 35's with 3.55 gears with the same 6-speed trans you got, and I kick myself every day for not getting the 3.92's . . . The trans spends half it's life searching for the right gear and shifting . . . I can't imagine how bad it would be with 37's

 

[R/T_Fire]

The trans spends half it's life searching for the right gear and shifting . . . I can't imagine how bad it would be with 37's

That is a good point on the trans not knowing what gear to sit in.. Had that issues on my Yukon I had.... Drove me nuts. and it had 4:10's with 35's. Damn GMC.

But it will not break anything but put excessive wear on the trans hard parts. I would recommend going to a lower gear.

Ans someone please correct me if I am wrong but for a 2012 isn't a 3.92:1 the lowest option available for the front dif? I remember reading it on the forum and being that I don't have a 4x4 ram I'm not on top of the new products coming in and out. I was not successful in finding a gear that will fit a 2012 diff with a quick search.. only up to 2010 models

 

[BOWERSFJ]

Ans someone please correct me if I am wrong but for a 2012 isn't a 3.92:1 the lowest option available for the front dif? I remember reading it on the forum and being that I don't have a 4x4 ram I'm not on top of the new products coming in and out. I was not successful in finding a gear that will fit a 2012 diff with a quick search.. only up to 2010 models

For 2012, you are correct, 3.92's are the lowest stock gear. If he has stock 17" wheels, the he has the Outdoorsman, or the base package. Outdoorsman will have 3.92's . . . Would have to add the towing package to the base to get em. Now here's the kick in the pants for 2012 . . . Something is welded in the front diff of the 2012's, making a gear change very difficult, if not impossible. Best bet is to find a whole 2012 front diff with 3.92's, and then change the rear gears.

Bottom line, this is all a bunch of blah blah blah, if he's already got 3.92's, and only the OP has the answer to that one.

 

[VanCityRob]

I have 3.55, I have a sport model and it had 20" stock rims but it's got 17" after market rims now.if Bowersfj is having problems with 35s than ill probably have a problem with 37s

 

[R/T_Fire]

I have 3.55, I have a sport model and it had 20" stock rims but it's got 17" after market rims now.if Bowersfj is having problems with 35s than ill probably have a problem with 37s

Get some real life numbers as to what the costs are for a shop to do the conversion, I'm sure that will help you decide on tire size to go with. I forgot or didn't notice of what trans you had. Even with 3.55's you may have some hunting issues. I'm not to sure.

This may help a little
Jaw

I just noticed that link doesn't have Ram info.. I'll see if I can find another

http://www.jeep4x4center.com/jeep-tires/tire-gear-ratio-chart.htm

I'm trying to find one where you can enter in the gear ratio of the trans vs tire size to tell you the best dif ratio.. Ive seen one but cant seem to find it now.

 

[Rzrman328]

I have 3.55, I have a sport model and it had 20" stock rims but it's got 17" after market rims now.if Bowersfj is having problems with 35s than ill probably have a problem with 37s

I don't think he was having problems...just wasn't pleasant to drive with the tire/gear setup he had.