wheel lip size formula? and offset question?

[phanatikz32]

is there a formula for calculating wheel lip size? in the future i want to get some deep lipped wheels but it seems like a guessing game on what offsets will give me the lip i want. i understand that the lower the offset the deeper the lip but i dont want to guess on a size and be wrong. and end up with wheels i dont like. for example how do i tell what the lip on a +6 offset will look like over a -10?

also i wanted to know do negative offsets put more stress and on your suspension? it seems that if the center plate for the wheel is further back in a negative offset that the actual wheel itself would sit further out putting more stress on the studs and the suspension and causing the wheel to lean in a bit or the knuckle to come down causing - camber like a teeter tater... i'm not sure if you'll understand what i'm saying but i'm not quite sure how to explain it

ok lets say that this "0" represents the center cap where the wheel bolts on and "_________________" is the with of the wheel

so this would be a 0 offset ____________________-----------0

would bringing the center to a - offset mean there is less wheel under the suspension and under the car like this? causing the wheel do lean in.. __________________-----0 i suck at explaining things but hopefully you guys understand what i'm saying....

[simmode1]

I understand what you're say and I've been wondering the same thing too!

You know what I wanna know? If you have front wheels that are 17x9.5+18 but your rear wheels are 17x10+38, will the lower offset fronts give your car a broader stance in the front than the rear? Kinda like a reverse stagger?

[Rex]

Unfortunately not.

The design of the wheel can create larger lip. An example is a current Sportmax/XXR wheel that comes in +35, but offers 2 different lip sizes for the same exact style, width and offset. They just offer one as a "rear" with a larger lip?!?!?

[phanatikz32]

i actually have those sportmax/xxr 006's on my car and it is like that. i suppose you can make decent lip with a higher offset thats why i dont understand how offsets really work. basically absolute 0 is the dead center from each edge of the wheel correct? so when someone says a - or + 6 offset would that mean 6mm from the dead center in either dircetion? what do the numbers even mean? if so then i guess you can calculate lip size by just adding or subtracting the size of the offset from the center. but i want someone to verify this is correct because i've seen some fitment charts that say "rim depth" but the numbers they give in mm dont correspond with the offset size so is that number for the size of the entire wheel and the offset is from dead center to wherever the center piece is? im confused...

[Rex]

Try reading through thishttp://www.nicoclub.com/tech/wheel-tech.shtml

[IanS]

also i wanted to know do negative offsets put more stress and on your suspension? it seems that if the center plate for the wheel is further back in a negative offset that the actual wheel itself would sit further out putting more stress on the studs and the suspension and causing the wheel to lean in a bit or the knuckle to come down causing - camber like a teeter tater... i'm not sure if you'll understand what i'm saying but i'm not quite sure how to explain it

ok lets say that this "0" represents the center cap where the wheel bolts on and "_________________" is the with of the wheel

so this would be a 0 offset ____________________-----------0

would bringing the center to a - offset mean there is less wheel under the suspension and under the car like this? causing the wheel do lean in.. __________________-----0 i suck at explaining things but hopefully you guys understand what i'm saying....

Ok, what you are asking about is immensely complicated.

When you change the width and offset of a wheel, the primary thing you are changing is what is called the Scrub Radius.

The scrub radius is the measured distance between the steering axis's centerline, and the center of the contact patch of the tire.

As you decrease offset, you increase the scrub radius. Most OEMs aim for a near 0 SR, and this is why factory wheels are le sunk.

As you increase scrub radius, funny things start to happen, many of these things are more noticeable on the front of a car as opposed to the rear.

The biggest change on the rear, is the extra wear placed on the wheel bearings. Also, in theory, by pushing the wheel out, you increase the lever length of the LCA, thereby reducing the effect of a given spring rate. This translates to more body roll.

On the front, things really get crazy. You still have added bearing wear, but now the wheels have to turn to. Things like bump steer, kickback, directional brake dive, increased steering effort, and many others can become problems depending on how far you push things. I could go in depth, but I would be here all day.

Hopefully this was at least a little helpful.

[phanatikz32]

thanks that info was pretty helpfull but i have another question that correlates. so you said that the SR is determined by the distance between the center of the contact patch and the center of the steering axis if this is the case couldnt you fix the problem of added SR by simply subtracting camber for example:

if you push the sr out by spacing or wide low offset wheels your contact patch center would be on the positive side with a 0 or positive camber like this:____________l____________l______________l______________l

couldnt you just add neg. camber to cause the wheel to lean inward thus bringing the contact patch center closer to the center of the SR? understanding that - camber does lower the contact surface if used in excess but regarldess the center line for the contact patch would still be closer to the inside? this seems to make sense and would give logical reasoning to doing ridiculous -camber when running wide wheels other than to clear fenders or look "jdm tyte" but correct me if im wrong...

[IanS]

thanks that info was pretty helpfull but i have another question that correlates. so you said that the SR is determined by the distance between the center of the contact patch and the center of the steering axis if this is the case couldnt you fix the problem of added SR by simply subtracting camber for example:

if you push the sr out by spacing or wide low offset wheels your contact patch center would be on the positive side with a 0 or positive camber like this:____________l____________l______________l______________l

couldnt you just add neg. camber to cause the wheel to lean inward thus bringing the contact patch center closer to the center of the SR? understanding that - camber does lower the contact surface if used in excess but regarldess the center line for the contact patch would still be closer to the inside? this seems to make sense and would give logical reasoning to doing ridiculous -camber when running wide wheels other than to clear fenders or look "jdm tyte" but correct me if im wrong...

Just one teeny tiny flaw in your logic. Any time you adjust camber, you also change the steering axis.

By adding a low offset wheel, you push the contact patch out, thereby increasing scrub. If you were able to adjust camber without adjusting steering axis, adding negative camber would increase the scrub even more.