What's the Backspace for 17" wheels/ W/ 6" lift kits.

tschreck said:

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OK, can somebody tell me if these widths, offsets, and backspacing combinations will work without sticking out too far and without rubbing if I went with a fairly aggressive and large 33" tire.

They are for the KMC Hoss

Diameter | Width | Bolt | Offset | Backspace | Hub Bore
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17" 9" 6x139.7 5.71" +18mm 78.1mm
17" 9" 6x139.7 4.53" -12mm 78.1mm

Click to expand...

Yeah Lou is correct.

The stock offroad rims have a 5 3/8" (5.375"), backspacing, (measured the spare under the truck with a straight edge across the rim and a tape to the mounting flange).

The offset of these rims is +30 mm. By calculation 7.5" + 1" (for the lips) is 8.5". So their center line is 4.25". Add 30mm of offset and the calculated backspacing is 5.43". Calculation is 0.055" greater than measured ... 55/1000", or less than 1/16" ... darn close.

5.71" b.s. rims' inside lip will be closer to the steering knuckle/spindle, and so are more likely to rub ... cause the tire to rub with wider tires, say like Toyo MTs. If it does, only a wheel spacer will help. Also, a wider rim allows the tire to reach a greater width, so even though this b.s. isn't that bad compared to OEM, ~5/16" more, a tire's side wall width will be 0.6" wider on a 9" rim, (half of which will stick out more at both sides of the wheel). So 5/16" plus 0.3 or another 5/16, is 5/8", (closer to the knuckle than if the same tire was mounted on the Off Road rim).

4.53" b.s. will ususally require the pinch-weld-mod at full steering lock, even with a 6" lift. My friend has the Moto Metal 951 with 4.5" b.s. and a 6" PC, with BFG 35x12.5x17 MT KMs, and he had to trim "a little". I've heard of leveled Titans with the same rims and 33" Nitto Grappler ATs in a 295/70/17 rubbing. But since you plan 33" with the lift probably very little trimming. Might look a little strange with 33s on a big lift though, since that is the stock diameter.

But the pinch-weld-mod that Kartman posted on this forum looks simple. They will stick out about 2.34" more than the stock on their outside face and about 0.845", (27/32" or almost 7/8") more than stock on their inside face.

They will give the truck more stability, due to almost a 2" wider stance, and with a lift this is good. And it will make the truck look way better too. IMO