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3.5" Lift - Tires Question

A

arfinsd

NAXJA Forum User
Location
San Diego
I have a RE 3.5" Super Flex lift installed. I'm currently running some stock tires. It's time to get some bigger tires. I have D30 up front and a Chrysler 8.25 (29 spline) in the rear with a 3.55:1 gear ratio.

The question I have is, if I go with 32's, will I have to re-gear? Should I go with 31's?

I don't mind trimming fenders, but I don't want to have to re-gear at this time. Help Please?

Alex
 
If you go with 31"s, you should probably regear. I ran around for a little while with stock gears, and it was miserable. I hated it, and I have a stroker in my XJ even. Regeared to 4.56's and killed my top end, but couldn't be happier. Now I just 55~65 on the FWY's and that's fine.

Just regear and be done with it. And go deep. 31"~33", definitely go with 4.56's.
 
well when it comes to increasing tire size, in all reality, you don't NEED to re-gear...

but you most likely WANT to

depending on your application (i.e. wheeling, DD, etc.) you can choose the gearing that would be most desirable for YOU...you can choose gears to aid gas mileage, or go to a deeper set for more low-end torque...

all in all, there is very little difference between most outside diameters of 31's and 32's...the difference is in rolling weight as there is simply more rubber involved with a wider tire...

so...you don't NEED to regear (unless you abuse your skinny pedal)

good luck
 
Yeah i have 2 friends one with a 3.5" and one with a 6" lift, both have 33's and run stock, they don't mind normal travel but wont go far. The 3.5" is a 5 speed and the 6" is an auto he doesn't mind it as much.
 
Running around on 31's with stock gears is like towing a utility trailer uphill, everwhere you go.

Your gas mileage goes to hell, your trans is constantly overworked, etc.

Even at 31's, gears will pay for themselves.

I ran 32's with stock gears and got like 14 mpg. Regearing to 4.56 it went up to 21.
 
So the answer is

NO you won't HAVE to regear. There will be benefits from the regear but it won't be required. Its not like 44's on a superduty where you WILL kill your trans. I have 33's and stock 3.55's with a AW4 and its not great but its tolerable. I have lowered fast cars and I am still saying its tolerable its not like I drive a big rig for comparison.
 
I'm driving 3.55's on 31x10.50 Trxus MTs which are actually 31" tall unlike most 31's. It really isn't that bad in my opinion. I mean it is noticeable, but far from intolerable. I wouldn't mind regear maybe this summer if I have the time and money, but I'm really in no hurry.

I wouldn't however go any bigger on stock gears. I still don't think it's that bad, but I wouldn't want it any worse.
 
silverslk said:
So the answer is

NO you won't HAVE to regear. There will be benefits from the regear but it won't be required. Its not like 44's on a superduty where you WILL kill your trans. I have 33's and stock 3.55's with a AW4 and its not great but its tolerable. I have lowered fast cars and I am still saying its tolerable its not like I drive a big rig for comparison.
Click to expand...

But that doesnt change the fact that it is really bad for your transmission and kills your gas mileage.


You don't know how bad it is until you do it and then regear. Once you have proper gears you will be amazed at the difference and kick yourself for not doing it sooner.

Gears are the single best investment you can put into a rig that sees any pavement time at all. Not only is it amazing for driveability, it will pay for itself in economy.
 
cal said:
Running around on 31's with stock gears is like towing a utility trailer uphill, everwhere you go.

Your gas mileage goes to hell, your trans is constantly overworked, etc.

Even at 31's, gears will pay for themselves.

I ran 32's with stock gears and got like 14 mpg. Regearing to 4.56 it went up to 21.
Click to expand...

When you figured you gas mileage had you corrected your speedometer after the gear/tire change?
 
I do think the stock gear (3.55) is all that bad with 31's. Ii would not regear. 33's: whole new ball game, after you kill both diffrentials then you can regear the new ones!
 
i have 31's and 4.10 gears and its pretty great. i wouldnt go lower than that. it runs about 2300 rpm at 70ish on the highway and it will usually spin a tire from a stop.
 
Wow, so many people saying that stock gears are okay, except for those of us that HAVE regeared. :D

How exactly can you offer an opinion on something that you haven't done?

Cal is exactly right on ALL of the reasons he gave for regearing.


























Just regear and be done with it. You'll be really pleased that you did. And remember, 'Deeper Is Better'. :D
 
theNAST1EST said:
well when it comes to increasing tire size, in all reality, you don't NEED to re-gear...

but you most likely WANT to

depending on your application (i.e. wheeling, DD, etc.) you can choose the gearing that would be most desirable for YOU...you can choose gears to aid gas mileage, or go to a deeper set for more low-end torque...

all in all, there is very little difference between most outside diameters of 31's and 32's...the difference is in rolling weight as there is simply more rubber involved with a wider tire...

so...you don't NEED to regear (unless you abuse your skinny pedal)

good luck
Click to expand...

Re-read the original post. He's running stock size(27"~28") tires right now and is going UP to 31"~32" tires. That's a pretty big jump in diameter.
 
If you don't want to regear yet, stick to the 31's. The additional weight and OD of 32's may be bearable to some, but you'll be better off smaller on stock gears.

I'm running 31's on stock gears right now, around town there is an obvious difference and it sucks the gas. On the highway I get better mileage. Since I drive around town 90% of the time, I'm regearing as soon as I can get the $ together for gears & lockers.
 
SBrad001 said:
Wow, so many people saying that stock gears are okay, except for those of us that HAVE regeared. :D

How exactly can you offer an opinion on something that you haven't done?

Cal is exactly right on ALL of the reasons he gave for regearing.




























Just regear and be done with it. You'll be really pleased that you did. And remember, 'Deeper Is Better'. :D
Click to expand...

i completely agree!

i had 3.07 in my 89 5sp with 31's for about 6 months and thought it was ok/doable. when i had the axles regeared to 4.10's, i was pissed that i waited so long.

just ok or doable really means, it sucks balls!

until you regear, you dont know what your missing.

also, running larger tires with stock gearing increases the load put on the drivetrain due to mechanical advantage.

yes it sucks to shell out the money for regearing, but its really worth it
 
whithin a month of running 30's on mine, granted its a 2.8 w/3.55s my gas mileage went to crap im lookin at put $10 bucks in and 15-20 miles from gas station and puttin in more gas and no power on hills lucky if i can hold 50 in 3rd gear.
 
smccollamjr said:
When you figured you gas mileage had you corrected your speedometer after the gear/tire change?
Click to expand...


Yes, and checked against GPS to make sure its approximatly correct (my speedo reads a couple mph slow actually, so I'm really getting a little better mpg; but close enough).
 
theNAST1EST said:
depending on your application (i.e. wheeling, DD, etc.) you can choose the gearing that would be most desirable for YOU...you can choose gears to aid gas mileage, or go to a deeper set for more low-end torque...
Click to expand...


Thats exactly the point here though. The low end torque gears ARE what aids gas mileage. The 4.0 will get better mileage spinning faster than working harder 10 out of 10 times. Given say, 32 inch tires, which mathmatically fall between 4.10 and 4.56 for "stock" equiv gearing - 4.56 will get better mileage. 4.10's will leave you with lower RPM's on the highway, but you use more gas to maintain them, so there is a net loss in economy.
 
I have this combo (3.55 and 31's). It bites. Even the hills in Michigan bites on the freeway with the AW4 down shifting and such. I can not even imagine what it is like in the Mountain States.

I also have the dreded D35 so the regearing will happen when the D44 goes in. I will then go 4.88's.

After being geared on the tall side for a while I want to go deeper for a while.

When the pocket book recovers from gearing.... I will step up to 34 or 35 inch tire.
 
One of our locals ran 4.88's with 31's for a while, even 1000 miles of highway to/from the Rubicon in 2004. You didnt see much over 65 mph but it was "more tolerable than expected". ;)
 
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