tire size (ratio) question

[turbotyla]

My jeep in not lifted yet. BUT before i lift i would prefer to gear and lock both front and rear.

 

So my question would be i have 31s at the this time. and i am wondering what is a a good gear ratio to go with to keep now. And still be able to daily drive with being able to up size in tires and not rear gear.

 

If i went with say a 3.73 gear that would be ok now but would it be ok after i lifted and went to 33s ? or would 4.10s be a better gear. ?

 

i have a 5 speed tranny. so could i still get decent gas mileage around town with 4.10 and what rpm would i be running with 4.10s at 65 ?

 

Or what tire size would i need to get to to get decent gas. or decent rpm at 65. with 4.10s vs 3.73

[BLHTAZ]

Which engine do you have?

 

:idea: You may want to put your basic Jeep spec's in your sig if you want to keep asking questions that require us to know what engine, tranny etc, etc... that you have ;)

[Pete M]

Unless you go to 4.88s, I wouldn't worry all that much about the ratio affecting your fuel economy. :thumbsup: Higher engine rpm does NOT directly equate to more gas being used, since the injectors will likely be pumping in less fuel per stroke because it's easier to maintain speed.

 

The best gas mileage comes from small tires with non-aggressive tread. Anything you do after that will only hurt. Maybe not much, but generally it's hard to beat stock.

 

Also, if you have one, please don't spend any money on a Dana 35. Invest your money into something that will last.

[turbotyla]

yea i do need to update my sig and all that but i have never really messed with it. I have a 4.0 renix 5speed

 

And i am not trying to go for better gas i guess i worded that wrong i just want to be able to still do 55 if needed. so what tire size would i need to get that with 4.10s or 3.73

 

And i have a rear 44 and i might be getting a hook up on another front axle from a friends shop.

[Eagle]

I put 3.73 gears in my '88 MJ to run with 31s. The overall final drive ratio is exactly the same as running stock tires with 3.55 gears. It's a good choice for street use, but not enough gear for off-road use with 31s, and definitely won't be enough gear with 33s.

 

If you're even thinking about 33s, go for 4.10s of even 4.56s.

[mvusse]

With the 5 speed, won't hist stock gears be 3.07? I though 3.55 was only for the auto.

[Pete M]

3.07 is the stock gears for a 4.0/stick, but I would never try to match that in the charts. 3.07s suck and I wouldn't want the same tire-to-gear ratio as stock.

 

 

Given the circumstances above, I would do 4.56. I have a 4.0/stick with 33s and 4.10s and I'd like a bit more gearing. With 31s it should be fine. There are factory rigs out there (the Isuzu Rodeo comes to mind) that came with 4.10 and even deeper gears and they had tires smaller than 31s.

[Eagle]

With the 5 speed, won't hist stock gears be 3.07? I though 3.55 was only for the auto.

That's correct.

 

But if you run 31s with 3.73 gears, the MPH per 1000 RPM is exactly the same as an automatic with 3.55 gears and stock tires. Which really isn't quite enough gear for 31s, and definitely isn't enough gear for 33s.

[BLHTAZ]

If you are going to stay with the 31's, then I would go with 3.73.

If you are intending to go to 33's, I would go with 4.10.

 

I have 4.56's with 35's with a 4.0L, AX15 in our YJ and it is more than enough gear so I would not want to run 4.56 with 33's. Actually, I did run 33's on the YJ for a short time and it cuold start out in 3rd gear with no problem on flat ground.