Hey so I have a 07 jku ive been running 37s on and I had the oppertunity to jump to the 40 so I did. I have a dana 60 conversion that is currently in the works to replace the front axle and a spare 44 incase anything breaks back there. Eventually I will put a 60 there too. Anyways I just sold the 37 and rims and I am going to have to run the 40's on the Dana 30 until I get the 60 put in. I know its dangerous and not ideal but its onroad only and limited driving until the 60 is in. Anyways I need to get a set of cheap rims to run the 40's on. They are the 40x13.50x17 Toyo Mt. and I am going to get a steel rim.

Choices for rims

Cragar 17x9 5.0 backspacing with a 1.5 spidertrax = 3.5 backspacing
Cragar 17x9 4.5 backspacing with a 1.5 spidertrax = 3 backspacing but a narrower rim
Pro comp 17x9 with a 4.25 backspacing and a 1.5 spider = 2.75 backspacing

I get I will lose some turning radius with it but which set up will work best for me to run these as just a street tire for now until the 60 is in and I can worry about flex and all that jazz.

 

for starters ...you will have axles with a different width and bolt patterns...you were really pushing your luck on the 37s so my guess is you don't really wheel it,you have to address the steering on 37s so you should already be set up there for the 40s...also the rear axle takes the majority of load and is the axle you should address first,rear stock axle width is 66.5 inches with a 5x5 bolt pattern,in general a d 60 runs around 68 inches in width...you can run wheel spacers in the rear but this will most likely result in toasted bearings and bent axleshaft flanges...hey...you may never be able to wheel it,if you ever even did but at least it will look cool

 

I do wheel but I am also on a limited budget. I was able to pick up a spare rear axle for 175 and figured I would put that on hold until I am able to do a conversion there as well... I know shit will break and that why I got the spare axle until I could switch. I run 37's fine and have no problems with my 30 what so ever. I will be first to admit I did not NEED to step up to a 40 yet but when you get the opportunity to sell your tires and rims and get 40s outright I am going to jump on it. It is the only opportunity I ever see myself having to make that jump. I will be getting spacers in the rear to convert the bolt pattern to an 8 lug as well and I know what the widths are... Guarantee you would do it too. So enough with the b**** answers. I know the obvious. I know what the risks are. I'm simply asking a question about the backspacing.

 

Give me the 40's and your problems are solved.

 

Nope you got axle shafts rather than replacing your axles like you told me. Liar.

 

I said multiple times next summer. I'm not as in a big off a rush as you are to run 40's.

 

Ummm why do you ask question if you dont like the answers you get? Lol

 

40s on a D30

 

bs answer huh...the info i gave you was 100% correct...don't get upset because i dont' agree with half a**ing a build..you are the one who posted this ..like i said,your wheeling your d30 on 37s with no problem proves you don't wheel it but most likely you just don't know what wheeling really is and you truthfully think you are doing something there...thats your thing and thats ok with me but don't get upset when you post a thread called how to run 40 inch tires and then when someone gives you correct info get selective hearing and bit*c about it..while we are at it i forgot to mention you may also have to extend out your control arms to get the most of your uptravel...thats what i had to do to mine for my 39 inch bfg krawlers anyways...

 

I think the minimum back spacing will need to be 4.5.

Huck