99 xj 185,000 3.5 lift 31s aw4 np242 hp d30 C8.25


Hey all,

Currently I am at 31s & 3.73s. I am at a dilemma on gear choices. I would like to keep the 31s for winter tires and get some 33x10.50 for summer/ wheeling. This leaves me with two gear choices with my current axles- 4:10 or 4:56.
I know there are rpm calculators and such, but im really looking for your experience on using these tire combos on these gears. Pros cons regrets no regrets.....

If 4.26 was and option i would likely have my mind made up. Is one or the other too little or too much for a DD. btw im in CO.

thank you for your assistance.

How much daily driving or highway driving do you do?

4.56's are perfectly suited for 33's in my opinion, however I don't think you'll find it being much of an upgrade going to 4.10's since you're already running 3.73's. Would be a considerable investment for a marginal upgrade. I'd go with the 4.56's and call it a day unless you do a ton of highway driving on the 31's.

Mostly I spend two 30 minute trips to and from work a day. Most of the drive is 55 max. I25 when needed is 75 MPH max. I know my 32s made the trans pissed off of on highway. 3000rpm 70-80 Ish. 3000 isn't horrible but I don't think it should be a usual consistent rpm.

Here is a vid a did awhile back when I had 32" 4.56 gears.. Cruising around wasnt bad.

The 4.56 gears with a 33x12:50 tire is about the same as the stock gears that came in your XJ on the highway and a better choice for off road for sure. That is the same combo I ran and going from a stock gear to the 4.56's gained me about 4-5 mpg on the 33's.

if i go 4.56 when i have my 31s on it would be like having stock 4.11s. is this gearing going to dog my MPGs?


Duma ive actually seen that video and it was helpful but what happens when you try going faster than 70? also you said had, did you change them for any DD reasons?

When your 31s wear out, perhaps just get a 33 inch tire for winter as well. That way you have 33s across the board. I say 4.56 as well

Very good point and with the proper tire you could run the same one year around and still be pleased with the performance under both conditions.

Just an FYI but have found over the years that a lower gear ratio is a better choice than not enough on a 4x4.

I have 4.56's in mine and used to have a set of 31's with summer tread that I would run on the road. Yes the RPM's were high on the interstate, but hardly ever took it there, and when I did I didn't even come close to 75mph. 60-65 was manageable.

I'd rather run back roads in the Jeep anyway, and I love the 4.56's offroad with my 34's.

Nothing happens I go faster.. I jumped to 33" and Im back to the stock feel with 4.56.. Its still my DD.
the 32" 4.56 did fine. I just went bigger just to go bigger. Nothing from daily.. I drove alot with the 32"

Yes I could run the same tire year around but I'm trying to use two sizes to save money. In the summer I want to run a 33 mtr tire for weekend wheeling, the 31s for winter. I had 32 Kevlars and the road just killed them.

ok but why? Driving half the year on 33s and the other half on 31s and wanting to regear though? Half the year you'll be geared wrong, so why spend the money to be geared right for half the year ya know? That's just me though man. Either way I'm gonna say go 4.56

I hear ya martlor, like I said if 4.26 was an option done deal unless any company cuts to application. asking for everyone's real world advice because I don't want to invest poorly by overgearing or under gearing. Either way 31s are not the proper match with 3.73.


anyone on or has run 33 & 4.10?

33's with a 4.10's is going to make your effective ratio feel very similar to your current gearing with 31's. (3.85:1 to be exact)


New tire diameter
_______________ X old axle ratio = new axle ratio.
Old tire diameter


Your current 3.73's in comparison 4.56's

4.56's on the 33's = 4.28:1
4.56's on the 31's = 4.85:1

go with the 4.10's. I ran 4.56's with 32's and 75mph was max i felt comfortably going. I commuted 80 miles a day with 40 of it being on I90. I always kept it at 70 and 2800 rpms. the time difference of 5mph over 40 miles was negligible. Someone would pass me, and take the same exit. By the time they left the stop sign at the off ramp, i was just exiting the interstate. With 4.10s, you will be fine with both tires, and even with 33's(which will eventually wear down to a 32) you will only notice a small difference, and maybe use 4lo a little bit more often.