Regearing and Tire Size

[Kannons610]

Regearing & Tire Question (Originally posted in incorrect forum)

I have a gladiator sport without max tow, so only 3.73 gears. I’d like to add larger tires without regearing, however I’d prefer not to drastically hurt ride quality, MPGs or stress the stock vehicle parts too much. I understand larger tires do change things, but I’d like to find a happy medium between larger tires and my other concerns. All of the gear calculators only ask for current gear ratio/tire size and new tire size. Does the new wheel/tire weight and width matter at all to regearing? I’m looking at getting a light (in weight) tire. My current 245/75/r17 are 31.5” in diameter. The new tires I have been looking at are 33.5” or 34.4”. Both are around 55-60 lbs. Any info you could share would be greatly appreciated. Thanks.

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[JTBurns]

So I have the 3.73's and have moved up to Rubicon takeoff Falken M/T's. I believe they're around 60 lbs, off memory anyway. You'll feel the truck works a little harder with them, especially up hills, but absolutely still love the ride and love the look even more now. The tire/wheel weight would matter with regearing since the vehicle has to work harder to move more weight, but I have no plans on regearing. If I did, I might as well try to find some rubicon axels since I'd get lockers with it. Jury's still out on how much more wear and tear this will cause, but I'd consider within the capability of the truck. I wouldn't go much bigger than 33's with this set-up, but I'm sure others do and I'd let them speak on that.

 

[Jack'D]

Sport S here.
Added a Rubicon suspension (shocks&springs), then put on some 285/70/17 Cooper Evolution M/T on my stock rims with 1.75" spidertrax spacers. Love the ride quality of the Rubi take-off suspension and it's a better look IMHO.
But I have also been considering going to 4.10 or 4.56 gears because I do want to tow a 3300lb trailer and the larger tires are a drag on the trans at highway speeds.

 

[mghoodlum]

I have welded trusses on both front (Artec) and rear (4 link Rock Crawler) and c gussets (Artec). I also upgraded to RCV with the FAD on front and Dana Chrome Moly for the rear shafts. I just installed 39” KO2’s which are a light tire for the size. I also regeared to 5.13’s. Based on what I have read the ring and pinion is probably the weak link but this setup should be better than any D44 before it. With the lighter wheels and not being to aggressive I’m hoping to get plenty of life out of this setup!

 

[jmdwifi]

I put 285s on my overland the day after I bought it. It rode fine and they were about 32 inches. I just bought new rims and put 35s on. They measure 34. It is noticeable and regear will be my next mod.

 

[USMC-SSGT]

I put 285s on my overland the day after I bought it. It rode fine and they were about 32 inches. I just bought new rims and put 35s on. They measure 34. It is noticeable and regear will be my next mod.

I also have 3.73 (soon to be 4.88) I’ve got 35” Baja boss which is a heavy tire. Around town it’s generally not noticeable. On the freeway or hauling/towing anything is awful. It’s a 100% need to regear setup. I’d say a light 33” setup would be just fine though since mine came stock at 32s. Still averaged around 21 or so mpg stock.

 

[jmdwifi]

I also have 3.73 (soon to be 4.88) I’ve got 35” Baja boss which is a heavy tire. Around town it’s generally not noticeable. On the freeway or hauling/towing anything is awful. It’s a 100% need to regear setup. I’d say a light 33” setup would be just fine though since mine came stock at 32s. Still averaged around 21 or so mpg stock.

Why not 4.56? just curious, I thought I would put this off but I see quadratic has 4.56 in stock for now.

 

[Panthers65]

IMO If you are going to make a gear change, it's really not worth it to step up one ratio(3.73 to 4.10 or 4.10 to 4.56). You'll need to jump 2 ratios to really feel a difference, and even then, it'll be a subtle change.

IMO I wouldn't spend a lot of time worrying about a 31.5 to a 33, Yes it would get it back to perfect but at the cost of a gear swap I don't think it would be worth it with normal driving.

 

[Fouts]

IMO If you are going to make a gear change, it's really not worth it to step up one ratio(3.73 to 4.10 or 4.10 to 4.56). You'll need to jump 2 ratios to really feel a difference, and even then, it'll be a subtle change.

IMO I wouldn't spend a lot of time worrying about a 31.5 to a 33, Yes it would get it back to perfect but at the cost of a gear swap I don't think it would be worth it with normal driving.

YES to this

 

[jmdwifi]

I’m on 3.73 with 35s. So should I go 4.88?

 

[USMC-SSGT]

I’m on 3.73 with 35s. So should I go 4.88?

General consensus from here and every single shop I spoke to was yes. This is straight from one of the more reputable custom 4x shops in the country.

“Sure thing! I’d definitely go with 4.88
gears; that 8 speed transmission loves it,
and will get you into 8th at a comfortable
RPM on the highway. And you are right on
the 37s, you’d still be good with 4.88s and
37s, and lots of times we go to 5.13 on 37s”

 

[jmdwifi]

General consensus from here and every single shop I spoke to was yes. This is straight from one of the more reputable custom 4x shops in the country.

“Sure thing! I’d definitely go with 4.88
gears; that 8 speed transmission loves it,
and will get you into 8th at a comfortable
RPM on the highway. And you are right on
the 37s, you’d still be good with 4.88s and
37s, and lots of times we go to 5.13 on 37s”

Thank you so much for the information. I really appreciate it.

 

[Jack'D]

Why not 4.56? just curious, I thought I would put this off but I see quadratic has 4.56 in stock for now.

Agree, 4.88 and 35's seems a little over the top for me, at 70mph in 8th gear that would put my RPM's at almost 2200! Over 2700rpm in 7th!!!
I also tow a trailer (KZ 181BH) dry its just under 3k lbs. I've got about 4200 miles on it this year with my current setup. Changing gears doesn't change the fact that the 3.6 has 260lb of torque (@4400rpm) here's the deal, even if I was running 2200 rpm's at 70mph the truck would still be upshifting on inclines, even at 2200 the truck doesn't have the torque for that kind of load. And when not towing 2200rpm would get really annoying and would probably knock my mpg down below 13. I think the truck, because of the 3.6, is a compromise, not the best 4x4, not the best truck, but it does both well enough.
37's with 4.56 gears would run about 1942rpm @70mph (35's + 4.10 @70mph = 1845rpm) wich is a lot closer to the 1865rpm the truck is optimized for.
I know 4.88s and 37s are the soup d'jour, and for the hard core off-roader, its probably a good fit, but for the daily driver crowd who goes off road a few times a year 4.88s might be over the top.
Just thinking out loud, im certainly not the expert on the subject.

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