so im planning on going to 35s here really soon on my jeep (1990 jeep cherokee) I want to get cragar soft 8s and im thinking 15X8s. So my question is if i run a 35X12.50 on a 15X8 rim what backspace do i need?? Also another question i have is what do i need for gears. My plan is to go 4.88s (also very soon) i have a d30 front and a 29 spline 8.25. So what all do i need to re gear to 4.88s? Im probably going to have the shop install the gears since i have no idea what im doing with them haha. any help will be much appreciated.

 

At least 3.5" backspacing.

4.88 in different axles, IMO.

 

And by at least he means <3.5" if you didn't know already, less backspacing means spaced out more

 

I'm running 3.75 inch backspacing in my 15x8 Cragar wheels. I have 33x12.50r15 tires. I recommend the same backspacing.

 

You'll most likely need a new carrier for the D30 depending on what your current gears are, the 8.25 doesn't have a carrier brake so you're good on it.

 

3.75.

I've got 15x10s with 3.75. I lovem. Great stability. I'm at 4.5" with 33 1250s

 

Okay so sounds like 3.75 for back spacing will be good? and lowrange2... why do you say i need different axels for the new gears? from what i understand the stock d30 and 29 spline 8.25 will be plenty strong enough for 4.88s.

 

He was referring to tire size not gearing. 35s will be fine on those axles for most people.

 

He is probably right, but it's gunna depend how hard you wheel it. I have the same setup as you, and just broke an axle shaft. Big tires are hard on the d30. I was pushing it to the max and broke. From now on I'm just gunna use it for beach driving and trail rides. We'd all like duel d60s, but it's not always feasible to make necessary axle swaps right away.

 

okay so i dont know a whole lot about gears. I know most of the stuff but what is a carrier?