Let me start by giving a little info on my build

I have the evo bolt on coilovers, synergy long arm, synergy tie rod-drag link- track bar

I have the ultimate dana spicer 60s coming my way

I will be running 40's, just not set on running 17 or 20in beadlocks yet....

The axles measure at 69in wms. I originally planned to run atx slabs in 17's with 3.5in backspace but recent info states the slabs do not fit over the brakes....

So this changes my options. Now i have found out that the trailready headlocks in 17's will fit but I'm contemplating going 20's with them. My question is with the 20x9.5 TR's and 4.5in backspacing be enough backspace to run 40x15.50r20 toyos and manage no higher than 4.5in of lift without rubbing issues ect...

Trailready 17's with 3.5 backspace net about 1.75 backspace and seems almost ideal for 40's and 4.5in lift.... 20's with 4.5 backspace net about 2.75 backspace and which lies my question as this seems to cause fitment issues.... Along with my question is the 17's are 8.5in wide and the 20's are 9.5in wide, i seem to recall reading that the wider rim allows for more backspace and helps with fitment but i can't confirm that?

 

I run 37x13.5x17 on 3" short arm and the tires rub frame and lower CAs with 4.5 BS.

Maybe CAs aren't an issue with a Long Arm kit but I would suggest contacting the axle manufacturer and ask them. Since the axle is a little wider it should keep you off the frame but I think you need to know where the lower CA mounts are going to be and what BS they suggest.

Sounds like a wicked build!!

 

I've read somewhere that the bore is different on the 60's axle. Something else to check on.

 

You will need a lot more back spacing. With a 69" axle and 40x13.50, you would need around an equivalent of 2.5" (so, a 4.5" BS wheel and a 2" spacer). You are going 15.50 wide, so you will need quite a bit.

However, if you are not stretching your front axle at all, you will have some issues with the frame as it curves out from front to rear. Dirtman should be able to give you a pretty good idea of what back spacing you will need. He has the same width axle and 40x13.50. Regardless, you are going to need spacers.

I'd suggest looking for a 13.50 wide tire or it will require some fairly involved fab work. Keep in mind that the turning radius of the 60 is likely greater than a stock JK axle.

 

With the 17x8.5 TR's at 3.5 backspace and 69in axles should net about 1.75 backspace, is this correct? And still need spacers? Maybe I'm looking at this wrong

 

I have found that I can get atx slabs in 20x10 with a backspace of 3.61 (-48 offset). My math puts a net backspace of 1.86 if I'm looking at this right. Hopefully spacers are not needed at 4.5in of lift?

 

Running a junkyard HP Ford D60 (69.25") up front with 4.0 BS on the Method wheels and 40x13.5x14 Toyo Open COuntry MTs. No rubbing up front and clears the extra large calipers.

 

The axle and frame mounts affect it aswell.

 

Good point - how much bump stop you run will make a big difference. I don't like to limit uptravel, sort of offsets benefits of modifications.

 

Shock travel will also have an affect as you will get more axle rotation. My axles are 68" WMS and I run 4.5" Bs wheels with a 1.5" adapter up front and a 2" in the rear on 3.5-4" of lift. 14" travel front and 16" rear shocks.