Budnik wheel backspace

[ShinyC10]

Wondering if anyone can shed some light on what they have run on their wheels backspacing, front and back. Ideally, I would like to have some sort of turn radius when aired out or a couple inches higher than completely aired out, if possible. I plan on having a bump step welding up to stop be a few inches from completely bottomed out. The back I’m just looking for the wheels to tuck as high as they can. Was looking at 20x8.5 and 20x10 budnik spyders. Tires, I was looking at 235/40/20 and 285/35/20. Thanks in advance

1986 c10 pickup
Front:
Factory control arms
Vannatta front inner fenders
Bags with plates and cups

Rear:
Stock bed floor, tubs and rear end width
Ridetech bolt in 4link with the shockwaves

[SCOTI]

5-5.25" BS fronts
5" BS rears (stock axle width)

First 2 pics are 20" Coys (8.5"F w/5.25"BS; 10"R w/5.5"BS).
Third pic is AR TT2's (18x8"F w/5.25"BS; 20x10"R w/5.0BS).

[ShinyC10]

Originally Posted by SCOTI

5-5.25" BS fronts
5" BS rears (stock axle width)

First 2 pics are 20" Coys (8.5"F w/5.25"BS; 10"R w/5.5"BS).
Third pic is AR TT2's (18x8"F w/5.25"BS; 20x10"R w/5.0BS).

Thank you for the reply. Exactly what I was looking for…couple questions. One of budniks install referrals is saying he remembers possibly 4.25 and to be safe 4.5bs, not sure if that’s the front or back, did not specify in our convo. The 20x10 looks like it’s exactly what I need. This truck on air ride or static?

[SCOTI]

Originally Posted by ShinyC10

Thank you for the reply. Exactly what I was looking for…couple questions. One of budniks install referrals is saying he remembers possibly 4.25 and to be safe 4.5bs, not sure if that’s the front or back, did not specify in our convo. The 20x10 looks like it’s exactly what I need. This truck on air ride or static?

Static drop w/a home-built air-over-leaf set-up for pulling a trailer.

If you're planning air ride & using OE length arms up front, you'll want more BS to tuck the wheels in from the fender lips. Narrowed a-arms & less BS works toward that goal as well.

[ShinyC10]

Originally Posted by SCOTI

Static drop w/a home-built air-over-leaf set-up for pulling a trailer.

If you're planning air ride & using OE length arms up front, you'll want more BS to tuck the wheels in from the fender lips. Narrowed a-arms & less BS works toward that goal as well.

So a 4.25 or 4.5bs up front is a no go for sure. I think I have read on here somewhere that 5.25bs up front on a 8/8.5 wheel is what some guys prefer.

[SCOTI]

Originally Posted by ShinyC10

So a 4.25 or 4.5bs up front is a no go for sure. I think I have read on here somewhere that 5.25bs up front on a 8/8.5 wheel is what some guys prefer.

Those numbers would work but you'll rub the fender lip sooner vs. w/more back-spacing. Not an issue w/a mild drop but can be w/aggressive drops.

[ShinyC10]

Originally Posted by SCOTI

Those numbers would work but you'll rub the fender lip sooner vs. w/more back-spacing. Not an issue w/a mild drop but can be w/aggressive drops.

So it’s sounds like with my current situation, the 5.25bs up front and a 5”bs in the rear will be ideal? As long as the width is still 8.5, does it matter if the wheel is a 20 or 19? I feel like the 20 is ever so slightly bigger than what I want up front and the 18s look just a tad smaller. Tires, I was looking at 235/40 and 275/35.

[SCOTI]

Originally Posted by ShinyC10

So it’s sounds like with my current situation, the 5.25bs up front and a 5”bs in the rear will be ideal? As long as the width is still 8.5, does it matter if the wheel is a 20 or 19? I feel like the 20 is ever so slightly bigger than what I want up front and the 18s look just a tad smaller. Tires, I was looking at 235/40 and 275/35.

Sidewall height would be my goal here. I target what is 'common' for OE manufacturers as far as sidewall height & larger diameter wheels (>17") which is typically around 4" tall. That height helps ride quality & pothole survivability. When you're less than 4" sidewall height, sooner or later a large pothole will bite 'ya & possibly mess w/your wheel investment.

235/25.4 x 40% = 3.7" (27.4" OD)
273/25.4 x 35% = 3.78" (27.57" OD)

I'd go 255/40 up front (28" OD) & 295/40 out back (29.2" OD).
More sidewall for pothole cushion + better overall height for the larger truck size wheel opening.

[ShinyC10]

Originally Posted by SCOTI

Sidewall height would be my goal here. I target what is 'common' for OE manufacturers as far as sidewall height & larger diameter wheels (>17") which is typically around 4" tall. That height helps ride quality & pothole survivability. When you're less than 4" sidewall height, sooner or later a large pothole will bite 'ya & possibly mess w/your wheel investment.

235/25.4 x 40% = 3.7" (27.4" OD)
273/25.4 x 35% = 3.78" (27.57" OD)

I'd go 255/40 up front (28" OD) & 295/40 out back (29.2" OD).
More sidewall for pothole cushion + better overall height for the larger truck size wheel opening.

Awesome, thanks for those numbers. So it seems like 5.25bs up front on an 8.5” width is ideal? The back looks like a 5bs on a 10” will work. Gonna call budnik in the next couple days to put me down.