Tires & Gears

[yellow_dolphin]

I am looking at getting some needed tires for my Scrambler. Engine 258, Transmission T5, T/C Dana 300, Differential gears 3.31.

If I get 31" x 10.5" tires:
- Do I need to regear to 3.73 or 4.10 with the 258?
- Do I need to regear to 3.73 or 4.10 if I was to swap to a 4.0L?
- What lift height so I use?

If I get 33" x 10.5" or 12.5" tires:
- Do I need to regear to 3.73 or 4.10 or 4.56?
- Do I need to regear to 3.73 or 4.10 or 4.56 if I was to swap to a 4.0L?
- What lift height so I use?
- Will I have any rubbing issues during turning or flexing?

Anyone has experience with the GoodYear Duratrac? Looking for an All Terrain tire.

Thanks in advance for the inputs.

 

[Randyzzz]

The Duratrack is an awesome tire-on the road, in the snow, and in the rough.

My philosophy on gearing is:

31"= 3.73, or 4.10 with overdrive.

33"= 4.10, or 4.56 with overdrive.

That's for a 6 cyl, a V8 can get away with a step higher gearing.
You can always get a bigger tire if the gearing is too low...

31" fits nice with a 2" lift, 33" with a 4" lift.

I'm sure there are other opinions/advice out there...

 

[AK-RWC]

Some CJs with the 258 came with 2.73, and stock 235/75R15 is roughly 29."

The difference between a 258 and a 4.0 is negligible when discussing gearing. But I agree with Randyzzz that you can get away with taller gears if you have a V8. You can also get away taller gears if you have an automatic since there is some effective gear reduction via the torque converter.

All that being said, what are you running now? If you have a four cylinder, they came with deeper gears from the factory to make up for the lack of power.

In my fiance's ZJ, she's got a 4.0 that came with 3:55. We bought it with a bad rear end and immediately swapped axles that were 3.73. Winter tires are 235s, and summer tires are 32"s. We can definitely tell that the Jeep is peppier with the smaller tires, but we also know that the speedo is correct with the 32"s, and the Jeep doesn't feel under-powered either way.

I've run 33"s with 3:73 and a V8 perfectly well. When I jumped to 35"s, I had to start using my 6.32:1 first gear on the street (I normally drive the T-18 as a 3-speed because first is SO low). I then went to 4:10s, and stopped using first gear on the street again.

I'm going to go to 37"s or 38"s and plan on keeping these gears for now, knowing that I'll just go back to using first gear for street driving.

My next gear upgrade will be to 4.88, and I plan on running 40"s.

As for lift, I'll give you the following advice, with the caveat that tire brands/models will vary in dimensions, and those dimensions will vary based on the rim you put them on. (My fiance's newish 32" BFGs are only about 1" shorter than my fairly worn 35" MTRs. Her tires are 11.5" wide on 7" wide rims. Mine are 12.5" wide on an 8" rim.)

31x10.5 will fit a stock CJ with no lift. it's close, but your sheet metal won't contact.

33"s will require a 2.5" lift. So long as you extend your bumpstops, you shouldn't have problems with rubbing during articulation.

Rim with and backspacing will impact rubbing on both your fenders and your leaf springs during turning. There isn't a universal rule; this is often just trial and error combined with vehicle-specific experience.

If I were you, I wouldn't re-gear or lift it running just the 31"s (unless you want to re-gear and/or lift). If you want the 33"s, you will need new gears. Look at your carrier breaks since that may influence your decision on 3.73s or 4.10s (or 4.55s), and decide if you want lockers since this will be the time to do it. I wouldn't go deeper than 4.10 with 33"s, unless you know you'll be upgrading to 35"s in the near future or you have an overdrive.

 

[tower210]

Duratrac

I just put a set of Duratracs on mine. I went 265/75/16 (which is a 32"). I haven't had it off road yet (still have some things to take care of first), so I can't speak to the tration issue yet. Very quiet, very good looking.

I have 2.73 gears, and given unlimited money (never happen) and unlimited time (eventually come close) I will likely change gearing to a 3.54 or 3.73. I've just been puttering around town so far, and it's actually pretty liveable with the 2.73. The 258 in mine is pretty strong, so that undoubtably helps. My gut feel is that 4.10 will be overkill on 31's unless you are going to live off road.

My 2 cents.

I am looking at getting some needed tires for my Scrambler. Engine 258, Transmission T5, T/C Dana 300, Differential gears 3.31.

If I get 31" x 10.5" tires:
- Do I need to regear to 3.73 or 4.10 with the 258?
- Do I need to regear to 3.73 or 4.10 if I was to swap to a 4.0L?
- What lift height so I use?

If I get 33" x 10.5" or 12.5" tires:
- Do I need to regear to 3.73 or 4.10 or 4.56?
- Do I need to regear to 3.73 or 4.10 or 4.56 if I was to swap to a 4.0L?
- What lift height so I use?
- Will I have any rubbing issues during turning or flexing?

Anyone has experience with the GoodYear Duratrac? Looking for an All Terrain tire.

Thanks in advance for the inputs.

 

[CBRogers]

For 33"s a ratio of 3.73-1 is good for the 258, but should go up to 4.10's for a 4.0l The torque curve is lower with the stock cam on a 258. The stock 4.0l like to run at a higher RPM with a stock cam. Something that they designed when moving to the XJ. Get the exhaust hotter to make the cat work better.

With 31's the 3.50-1 is a better choice, but you can actually get by with 2.72's and the 258 inline six. If you go to a 4.0 then consider moving to the next higher ratio.

I have 32's and 3.50's in the CJ and that works well on the road, 3.73's would be good with 33's on that one. On the TJ I have 33's and 3.73's that is a bit large for the cam in the 4.0l but if I did a cam swap it would be better.


Carl

 

[yellow_dolphin]

Everyone thanks for the awesome input.

I accidentally left some set up information out. Here is what I have:

82 Scrambler, Engine 258, Transmission T5, T/C Dana 300, Differential gears 3.31 in wide track axles, OEM chrome wheels 15 x 7(?), and a Rubicon Express 4.5" lift.

I am trying to figure out what size tire is the best for the existing set up and because this Jeep will not see any off-road any time soon I rather swap the suspension and not the gears. This is skill set (never re-geared an axle) and money driven.

What is better for the gears, wheels, and suspension I have, 31" or 33" tires?

Can I lower the 4.5" lift by changing the shackles or remove a leaf? Or do I have to change the springs?

 

[kimsanva]

Everyone thanks for the awesome input.

I accidentally left some set up information out. Here is what I have:

82 Scrambler, Engine 258, Transmission T5, T/C Dana 300, Differential gears 3.31 in wide track axles, OEM chrome wheels 15 x 7(?), and a Rubicon Express 4.5" lift.

I am trying to figure out what size tire is the best for the existing set up and because this Jeep will not see any off-road any time soon I rather swap the suspension and not the gears. This is skill set (never re-geared an axle) and money driven.

What is better for the gears, wheels, and suspension I have, 31" or 33" tires?

Can I lower the 4.5" lift by changing the shackles or remove a leaf? Or do I have to change the springs?

I've been running the 258/3.31/31" combo with no lift for a year with primarily local road use ~30 mile trips at the most. You're only turning ~1697rpm @ 55mph in 5th according to this Gear Ratio Calculator which look to be about 1600 on my tach. No problems with interstate speeds and crossing the Blue Ridge keeping up with traffic on the return trip from the Louisville purchase. Feels fine driving, but it's at the low end of the power/economy curve for the engine. I'm sure it's less than optimal for serious offroading.

I'm heading for 235/75/R15s when these are more worn. Should provide better ride/pep/economy and won't look too skinny. Just about perfect for my road and beach use. I've never been much on the "monster" look of oversized tires and jacked ride.

Someone else can answer you about the lift/lower situation.

Hope that helps.

 

[AK-RWC]

Everyone thanks for the awesome input.

I accidentally left some set up information out. Here is what I have:

82 Scrambler, Engine 258, Transmission T5, T/C Dana 300, Differential gears 3.31 in wide track axles, OEM chrome wheels 15 x 7(?), and a Rubicon Express 4.5" lift.

I am trying to figure out what size tire is the best for the existing set up and because this Jeep will not see any off-road any time soon I rather swap the suspension and not the gears. This is skill set (never re-geared an axle) and money driven.

What is better for the gears, wheels, and suspension I have, 31" or 33" tires?

Can I lower the 4.5" lift by changing the shackles or remove a leaf? Or do I have to change the springs?

I'd stick with 31"s given that combination. While you can easily fit 33"s, you're not going to like it on the highway. I have no experience with the RE 4.5" lift, but I wouldn't monkey with it. If you want it lower, get a different set of springs and shocks.

 

[Randyzzz]

Base questions...

What size tires do you have on there now? Do you like the way it looks? Do you like the way it drives?

I guess we need to start somewhere. There's a lot of good advice here, but a lot depends on personal tastes and driving styles. Case and point- My wife has been driving my Cherokee. 31" tires, 3.55 gears, 4.0 HO. She thinks it's peppy. She also gets fairly decent mileage. I bought it with 215/75/15 tires. It felt peppy then (would light the tires on dry pavement)...and got decent mileage for me. Now, with the 31"s, I think it's a dog. And, my mileage is way worse than hers.

So, tell us about where you're at now, and we'll come up with something...

 

[yellow_dolphin]

Base questions...

What size tires do you have on there now? Do you like the way it looks? Do you like the way it drives?

I guess we need to start somewhere. There's a lot of good advice here, but a lot depends on personal tastes and driving styles. Case and point- My wife has been driving my Cherokee. 31" tires, 3.55 gears, 4.0 HO. She thinks it's peppy. She also gets fairly decent mileage. I bought it with 215/75/15 tires. It felt peppy then (would light the tires on dry pavement)...and got decent mileage for me. Now, with the 31"s, I think it's a dog. And, my mileage is way worse than hers.

So, tell us about where you're at now, and we'll come up with something...

It is an 82 Scrambler, 258, T-5, Dana 300, 3.31 gears, OEM chrome wheels 15 x 7, Rubicon Express 4.5" lift.

Right now it has 235/75/R15. It looks dorky since it has a 4.5" lift and small diameter tires. It feels like it has power on the road. Have not taken it off-road and it is not a priority right now.

The truth of the matter is my '02 TJ got rearended and totalled. I need new tires for the Scrambler so I can drive it, but I am trying to stay away from regearing unless I can find the complete axles with the right gears inexpensively. Money is an issue. I had bought the 4.5" lift a few years ago, but I am not sure I am happy with it. I think 31" I will enjoy 31" tires on the Jeep but I am concerned about its driveability with the 3.31 gears. I know 33" will fit but again I am concerned about the 3.31 gears.

Thanks for everyones inputs. Keep them coming as they are helping.

 

[kimsanva]

It is an 82 Scrambler, 258, T-5, Dana 300, 3.31 gears, OEM chrome wheels 15 x 7, Rubicon Express 4.5" lift.

Right now it has 235/75/R15. It looks dorky since it has a 4.5" lift and small diameter tires. It feels like it has power on the road. Have not taken it off-road and it is not a priority right now.

The truth of the matter is my '02 TJ got rearended and totalled. I need new tires for the Scrambler so I can drive it, but I am trying to stay away from regearing unless I can find the complete axles with the right gears inexpensively. Money is an issue. I had bought the 4.5" lift a few years ago, but I am not sure I am happy with it. I think 31" I will enjoy 31" tires on the Jeep but I am concerned about its driveability with the 3.31 gears. I know 33" will fit but again I am concerned about the 3.31 gears.

Thanks for everyones inputs. Keep them coming as they are helping.

Just for a visual here's my 84 with 31s and "lifted" ~4.5" in photoshop:

33s would be a nice visual fit, but I think it'd feel pretty sluggish with 3.31 gears.

 

[Randyzzz]

Ok, so you're pleased with the performance of the 235/15 but not the looks. I think a 31" tire would not substantially degrade the performance, while adding a look that would not be out of place with the lift. It is my experience that the 4.5" lift seems to sag to about 4" or less after a while, but immediately after install seems to be more like 5.5".

Bottom line- 31" tires should be ok performance wise, if you're ok with the 235's . I'd buy them (or a cheap used set just tor try them) and see how it all feels. Looks wise I think it will be ok. Looks great in the above Photoshop example. 8" wheels would have been a bonus, spreads the sidewall a bit more and sticks out a bit farther, making the tire appear bigger.

 

[yellow_dolphin]

I will give the 31s a try. Thanks for all the input.

 

[Polarfire]

Just for a visual refrence, I bought my Scrambler with a 4" lift and 31x10.50 tires. I now have 33x12.50 tires.

31" tires:

33" tires:

 

[AllxHeart]

I'm trying to figure out what I need to run for tire size based on axle setup, gearing, engine, etc. I have a 82 scrambler that is getting a cummins 4bt, NV4500, dana 300, 14 bolt rear and Dana 44 front. The axles have 3:73 gears right now. With the spring over axle and stock Wrangler conversion leaf springs I'll be at 4 inches of lift at least. So 33's are going to look dumb under it with wider axles and the lift. I was thinking 35's but now I am not sure those will even look ok. I don't want to go more than 37's though. I'd like to keep my mpg in the 20's. I could always keep my AMC 20 rear and dana 30 front and just do 35's. Does anyone have any suggestions. I'm at a stand still right now. I have to either lift my jeep with the stock axles to put the engine in or put the 3/4 ton axles in with the wrangler conversion axles. Any advice is appreciated!