Ok, I know this has been discussed with bits and pieces spread through numerous threads, but I am honestly confused on a number of things here.

First, how do the offsets correlate to wheels widths? In other terms a +22 offset on a 10.5" wheel v.s an 11" wheels is going to put more of the wheel in a different direction, question is which way is the wheel going based on wheel width? As the offset goes up, does more of the wheel go to the inside? I am personally looking at 10.5-11.5 wheels and looking to put all my wheel on the inside, not out towards the fender.

How is the negative offsets figured? I was hoping there would be something in the sticky thread but it is very confusing, and one thing that definitely seems to be better understood by others in this section.

I do have Brembos also, so i'm trying to understand the entire concept before really looking at specific wheels.

Thanks in advance for all the help guys!

 

http://www.1010tires.com/wheeloffsetcalculator.asp type in specs and look, simple and easy.

Basically if you have a 10.5 +22 wheel and a 11 +22 the difference will be 1/4 inch on both the inside and outside.

 

0 offset is center of the wheel, so 0 on a 10 inch wheel is 5 inches - dead in the center.

0 offset -
Drivers side.............Passenger side
|-----0-----| ........... |-----0-----|
NOTE: So on a 10 inch wheel, the outside edge of the wheel will be approximately 5 inches from the mounting point. On a 9 inch wheel, it will be 4.5 inches away, etc.
How far will my wheel stick out with a zero offset = .5(wheel width)


+30 offset means that it is 30mm "shallower dish/lip" and the wheel is going to sit further inside the wheel well

+30 offset
Drivers side.............Passenger side
|---0-------| ........... |-------0---|
NOTE: So on a 10 inch wheel, the outside edge of the wheel will be approximately 5 inches minus 30mm from the mounting point.
How far will my wheel stick out with positive offset = .5(wheel width) - positive offset number


-30 offset means that it is 30mm "deeper disk/lip" and the wheel is going to sit further towards the outside of the car.

-30 offset
Drivers side.............Passenger side
|-------0---| ........... |---0-------|
How far will my wheel stick out with negative offset = .5(wheel width) + negative offset number

 

Wow, great information man, thanks for explaining it like that... Definitely able to understand it the way you put it.

 

Also, keep in mind that if you run a "fat" tire that is wider than the wheel, that will need to factor in as well (add the overlap of the tire).

My approach is different than most, but I just choose the offset to get the look that I want for the wheel (deep/medium/no lip). Then once I've mounted the wheel and tire on the car and had an alignment, I measure with a metric ruler to decide where I want the wheel in relation to the fender and I buy the appropriate spacer to get the overall look that I'm going for. Unless you're going with extreme negative offset for a huge lip, and superwide wheels/tires at the same time, it's a reasonable way to tackle the decision on offset & spacers.

 

What i'm trying to accomplish is a 295-335 wide rear tire with putting as much as possible on the inside of the car... I was looking at 11.5” wheels, but based on your explanation I would think that I would be looking at something like a +30 or greater offset, probably more along the lines of a +40 to +44 offset. Worst case scenario, if it is too far inside, I can always add a spacer.

 

I would suggest rolling and pulling your rear fenders. I run 285s or 295s on the rear with a 10" wheel +30 offset with 30mm spacer (so effectively a zero offset). I'm rolled and pulled and have maybe 3mm of clearance from scrubbing on the fender - sometimes I do rub in hard corners. I can run the wheels without the 30mm spacer without scrubbing on the inside, but it's close. So I would expect 315s or 325s would be possible without serious modification other than rolling and pulling the fenders.

Are you doing this for drag, for show, or is this a daily driver and you just want fatties on the back?

 

I have a roller and can roll my fenders, however i'm not sure that the pull will be easy enough as I just had the car painted last year, and with pulling I have only heard of doing so and breaking the paint. If there is another way to pull without breaking the paint I am open to suggestions for sure.

I need more tire on the ground because of my power levels. For the strip I am most likely going to be running MT drag radials, but for the street I want something to put my power down. My 255/45/18 KDW2's are not cutting it.

Are you running a suspension too, or are you on stock suspension with that sizing?

I appreciate all the help and responses too man, it really is a learning curve for sure.

 

A wheel with a negative offset looks like this. The hub mounting surface is toward the back or brake side of the wheels center line. The subject is seldom addressed because there is no room here for a brake calliper.

 

Not possible. The wheel-tire will not clear the suspension.

 

I'm on Eibach Pro springs with Ichiba camber arms and SPC toe bolts in rear, hope to go true coilovers later this year and add some adjustable A arms up front.

Also, as far as david's comment - completely true unless you're willing to do some abnormal things and wear through tires quickly - it depends on suspension, effective offset, fender roll/pull, camber/toe/caster.

Once you go over the 295 barrier, it becomes increasingly difficult to not rub on one side or the other. It is also hard to say what your limit will be, because there are variances from one car to another because of your bushings, alignment, etc. Just be ready to pull your fenders (possibly repaint if it cracks) and go through some tires (from rubbing or running weird camber to fit) while you're figuring out what is going to fit on your particular car's setup. Or just go with a 295 and a fender roll and call it a day.

Check out this thread for an idea of how the different sizes look. Most everyone posted their offsets as well, so that will be helpful for you - https://my350z.com/forum/media-share...ber-shots.html

 

In regards to a 295 which after going through that thread I think will be the optimal max tire size size I could run... What would be the best offset for a 10.5" tire? I'm looking at +18 to +22 for a 18x10.5. On a side note from what was mentioned above speaking about calipers, is there going to be an issue having OEM Brembos?

I think RPF1's or a Forgedstar F14 are what I have come to on a conclusion as far as wheel choices.

 

I don't think you can push the rear width quite that much. I just helped a friend with a wheel set-up, and now he is at > < close to the shock on the inside (so not much room for more offset OR more tire), and he needed his fenders rolled to clear on the outside. If you pull the rear fender, then you could go with a wider tire and a 10.5" wheel with less offset (or use a spacer) or an 11" wheel with less offset.

 

Well 10.5 +30 fits just fine, with the spring mounted on the shock (true coilover ) with room, i measured on my car (my Enkei NT03's are that size and offset without the spacer i run, Then you can easily extend another 20mm outside, 18x11 +25 would be simple to run with a 315/30-18

 

XXx11.5 +20 will be okay with a roll. and a 295/305 no problem.

 

To throw in curve ball, i'm looking to retain my stock suspension until the end of the season when I cage my car at the same time... Fenders will be rolled, would a 10.5 +30 still make it?

This is all really great info, you guys got the wheel setups down it seems!

 

Yes, you actually have more clearance with stock style suspension that someone like me with true coilover rear.

 

Awesome, looks like i'm going to go with 10 or 10.5 then with probably the +22 to +30 offset, that should be perfect with a fender roll and then when the time comes for suspension, it will all work together hopefully well.

Thanks guys!