offset question
#1
offset question
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!
#2
Ditto this from me. Lots of folks going with +40, +35, +38 in 15" x 6.5. What will this affect? I am assuming that if we go 10-15mm that it won't change much. How far can you stray from stock without adverse affects?
#3
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!
#4
The offset is from the middle of the wheel to the mounting plate. As the wheels get wider those numbers will change some to compensate for the wider wheel. Here is a link that explains it. If I can help let me know.
http://www.tirerack.com/wheels/tech/...jsp?techid=101
http://www.tirerack.com/wheels/tech/...jsp?techid=101
#6
It depends on how much room you have at the fenders. If you all ready have say a 16X7 wheels and you have to run a 10mm spacer then they may hit the fender. Also if you run too big of a spacer the wheels would not be hub centric.
#7
Originally Posted by jim@tirerack
if you run too big of a spacer the wheels would not be hub centric.
never used spacers I've only got aftermarket rims on my rsx and there was no need
#8
Use spacers with care to decrease offset but not increase. And take note that spacers decrease the thread engagement of your wheel studs. NEVER go below thread engagement equal to your lugbolt diameter. 3/8 spacers are likely to do that. As a general rule 1/4 is max with 1/8 common. A wheel with 42 mm neg offset will change to 39 with a 3 mm spacer. You cannot use spacers to increase offset.
#9
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!
Generally speaking, engineering concerns about bearing loads etc are minimized by keeping the inside edge of the wheel rim in the same place or inside as the stock wheel.The Fit's 6" rim width with 55 mm offset (2.16") puts the inside edge 5.16" inside the hub face ( half the wheel width, 6", plus offset). If you put a 7" wide wheel with 42 mm offset the inside rim edge will be 5.15" (7/2+42/25.4) inside the hub face so you are not going to increase bearing loads or torque steer by a noticeable amount. The weight load is distributed across the whole tread width not equally but substantially so bearings don't see a lot of difference.
However if you use a 6" wheel with 42 mm offset the inner edge will be 4.65" inside(6/2 + 42/25.4). Thats half an inch less than the stock wheel backspace of 5.16" so you will noticeably increase bearing loads and have harder steering as well as noticeable change in camber that may prematurely wear inside tire tread. Those will change handling characteristics.
That help?
Last edited by mahout; 06-20-2008 at 08:10 AM.
#11
Thanks in advance !
#12
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!
.
The key to avoiding wheel bearing and other engineering issues is to keep the back space equal to the original. The OEM Fit alloy is 15x6 with 55 mm (2.16") offset so the back space is 6/2 + 2.16 = 3 + 2.16 = 5.16"
A 7" rim on a wheel with 42 mm (1.65") offset has a backspace of 7/2 +1.65 = 3.5 + 1.65 = 5.15" so the wheel bearings are not realy stressed out of spec limits.
The reason for the 45 mm offset when dropped is merely to avoid rubbing problems, at least for tires up to 205 section. (We think the 17x7/205x17 conversion looks best.)
There is a possible way to avoid rubbing on dropped Fits with 42 mm offset wheels by making the shocks or springs so stiff there isn't really compression of the rear suspension. The best in my opinion is using Monroe AirLift MA-811 rear shocks (see the suspension posts). Stiffer springs will have an unpleasant ride.
Good luck.
Last edited by mahout; 06-20-2008 at 08:03 AM.
#13
Based on the 8 Fits we have equipped with aftermarket wheels we say 42 is the lowest offset allowed if you don't drop the Fit; 45 mm if you do.Some of these were complete wheel replacements for offsets below 42 mm. Expensive.
.
The key to avoiding wheel bearing and other engineering issues is to keep the back space equal to the original. The OEM Fit alloy is 15x6 with 55 mm (2.16") offset so the back space is 6/2 + 2.16 = 3 + 2.16 = 5.16"
A 7" rim on a wheel with 42 mm (1.65") offset has a backspace of 7/2 +1.65 = 3.5 + 1.65 = 5.15" so the wheel bearings are not realy stressed out of spec limits.
The reason for the 45 mm offset when dropped is merely to avoid rubbing problems, at least for tires up to 205 section. (We think the 17x7/205x17 conversion looks best.)
There is a possible way to avoid rubbing on dropped Fits with 42 mm offset wheels by making the shocks or springs so stiff there isn't really compression of the rear suspension. The best in my opinion is using Monroe AirLift MA-811 rear shocks (see the suspension posts). Stiffer springs will have an unpleasant ride.
Good luck.
.
The key to avoiding wheel bearing and other engineering issues is to keep the back space equal to the original. The OEM Fit alloy is 15x6 with 55 mm (2.16") offset so the back space is 6/2 + 2.16 = 3 + 2.16 = 5.16"
A 7" rim on a wheel with 42 mm (1.65") offset has a backspace of 7/2 +1.65 = 3.5 + 1.65 = 5.15" so the wheel bearings are not realy stressed out of spec limits.
The reason for the 45 mm offset when dropped is merely to avoid rubbing problems, at least for tires up to 205 section. (We think the 17x7/205x17 conversion looks best.)
There is a possible way to avoid rubbing on dropped Fits with 42 mm offset wheels by making the shocks or springs so stiff there isn't really compression of the rear suspension. The best in my opinion is using Monroe AirLift MA-811 rear shocks (see the suspension posts). Stiffer springs will have an unpleasant ride.
Good luck.
#14
If you were to stay with a 55mm offset wheel and the wheel is wider than stock they would then rub on the inside. The offset has to be adjusted so that some of the extra width is distributed toward the fenders.
#17
if you use 205/50x15 tires on an 08 you will likely have rubbing issues with 38 mm offset, ptrobably with 40 and the minimum you can get by with is 42, although 45mm is safest on a dropped suspension. The 15x6.5 is perfectly good to use with 205 section tires.
The offset counts most: with a 38 mm offset you are pushing the tire out 3/4" and a 205 is about 1/5" wider so you're looking at the tire moving out abn inch. Even though the tire is slightly less diameter (which helps in the acceleration and mpg departments)..
#18
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!
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.
Last edited by mahout; 03-04-2009 at 01:22 PM.