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Old 03-25-2010, 09:10 PM
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coax coax is offline
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Join Date: Oct 2008
Location: Estes Park
Posts: 750
Default Double Check My Math on Backspacing?

So with the winter season almost over, I am about ready to get a new set of wheels for the cruiser, leaving the snow tires on the OEM rims. As it seems finding sets of cruiser rims is a bit tricky, I started looking at the early 00's Tundra Rims.

Am I correct in that backspacing doesn't really matter too much in this instance? Its the offset that makes the difference? (Realize they are both tied together) Seems like the tire/wheel moves more than .6 inches of side to side just from the lift and not adjusted panhard. Plus the narrower rim would "narrow" up the tire a bit? (So maybe only shifting the tire .5" inwards?) Also seems like you could end up with .6" difference in just manufacture's variance. End goal is to run 285's without dealing with spacers.

I've got these specs so far:

OEM 80 Series Wheel: 0 offset, 4.5" backspacing, 16x8, 108 bore size.
Tundra Wheel: 15mm offset, 4.6" backspacing, 16x7, unconfirmed bore size of 106 or 110)

Centerline of tire moves inwards: 15mm/.6 inches
Inside of rim moves in: 2mm
Outside of rim moves in: 28mm

Did some searching on mud but couldn't find anyone running the Tundra alloy's, just the steelies And lots of folks were arguing that you needed 1.5" spacers. I don't understand that when the tire only shifts by .6 inches inwards? I guess to compound this the early Tundra Alloy's came in both acorn and shank style lugs? Am I correct in that a hubcentric/shank style wheel would require the hub and bore to be a perfect match so that the lugs are not taking a bulk of the up/down force?

Suppose another path would be to mount the summer/dirt tires on the Cruiser rims and mount the snow tires on the Tundra wheels, since they'd see less articulation when going skiing rather than desert travels?

Am I on the right path?

'97 lx450, 170k, factory lockers, ome 850/863, 285's, 4 working doors(1 more than the old fj55 )
'74 project pig (sold)

Last edited by coax; 04-05-2010 at 05:25 PM.
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