Quote:
Originally Posted by Chikubi
ok, so I understand what offset is, how it's measured, how it relates to the rim, but what I want to know is this -- the Fit's standard rim is 15x6 +55 offset, but the average offset for aftermarket rims is always much lower, i.e. the WedsSport SA90's on your site are a 16x7 +45. I've always been told that if you stray from the stock offset you have issues like bearing wear, torque steer, heavier steering, rubbing, etc., none of which I want. What I want to know is, how can you be using a lower offset wheel and not have these problems? Why are there no rims w/ a +55 offset like the stocks? If you go to a lower offset the centerline of the wheel is in a different place than stock, regardless of wheel width, so how does this not cause damage/handling issues? I really want to get some rims for my Fit, but not if it's going to ruin the handling, or even worse, cause damage. Can anyone clarify this for me? Thanks!
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The issues with lowered suspension and less offset wheels/tires are similar. Though not absolute they are good rules.
1. Moving the wheel/tire further out from the chassis does increase the loads on the wheel bearing. Unless you go further than 1/2" (that's 13 mm as in 55 to 42 mm)there isn't likely to be noticeable change in your bearing life unless you increase the vehicle and content weights carried by the wheel. And that presumes you will maintain the inside rim distance from the hub face as originally.
That means increasing the rim width to keep the same backspace. If your stock wheel is 16x6/53 you need a 16x7 wheel with 42 mm offset so the back space is still 5.15" (as it was with a 16x6/55 wheel. Note half the rim width plus the offset in inches are the same. That's the back space.)
2. There will be noticeable changes in the suspension performance when the wheels/tire are moved out too far. Ordinarily, the centerline of the tire intersects with the lower A-arm angle close to ground level for best performance as the wheel no longer follows the tire track arcs intended by the designer.
Pushing the wheel out can then cause the intersection below ground, which can cause some binding in the suspension movement.
3. lowering the suspension REQUIRES stiffer springs so the suspension travel is reduced to maintain minimum road clearance.. Otherwise you will be driving an unsprung wagon with subsequent handling problems due to both increased camber, abrupt suspension limits when the suspension 'hits bottom', or the is binding in the designed suspension movement.
A little lowering say an inch is good but more is potential problems. Additionally. when springs are changed, the shocks should be changed as well.
4. Changing tire sizes to big diameter and heavy tires aklso affects bearing life by increasing side loads on the bearing carriers besides decreasing acceleration and decreasing mpg's.
Hope that helps.