b's90cam

Has anyone run these on the front without any rub? i have a friend letting his go and i wouldn't mnd having them. I have the 2" spacers already so i'm thinking they'll bolt right on. the rims are z06 rims with 56mm offset

thanks
brandon

tomclf

It depends on the rim. I have a set of Z06 rims with the exact same measurements that you gave on wheels and tires. The offset is 56mm. With that offset I could not get 2" spacers to work on the front end. My car needed the 2.25 spacer to clear the tie rod end for 17x9.5 with 275/45/17s.

b's90cam

those are the whells i'm getting. 2.25 works for you? What about the rear. Same or 2"

thanks

also..., how quickly will i go through a set of 245 with daily driving?

tomclf

Well....... I am still figuring that out. I took the wheels off of the car and sent the adapters back. I am either going to go with a different size adapter for the rears or go with different rims altogether. The fronts cannot come in any more so that is as good as it gets. I am thinking of either the 2" or the 1.7' for the rears - I have to think through the measurements to see if it will work.

The problem for me is that I do not like to the tires to stick out past the fender or even sit directly under the lip of the fender since under intense driving conditions the tire is going to rub and possibly get damaged. And, it does not look right in my opinion.

Check out the picture.

I hope this helps,

Tom

tomclf

Tried to put up another picture but cannot for some reason.

tomclf

Here we go. For this wheel, I was able to slide the wheel in a little by adjusting the panhard bar but is still sat out quite a bit.

b's90cam

maybe i'll stick with my 8.5's

496ws6

whats the back spacing on those rims and what would be the absolute widest rim and tire combo i could run without it stick out furthour than yours is in this pic i luv how that looks.maybe just another inch or less at the most.

tomclf

Well - these rims are not given measured in inches for backspacing. They are given in an offset measurement in millimeters. The offeset for these rims is 56mm. That translates to 2.204724409448819 inches.

I think the way this works is to take the rim width (9.5) and divide it in half (4.25) and then add the 2.2 inches roughly from the offest measurement and then add another .25 for good measure - front lip of the rim. This all comes out to about 6.75 inches for your backspacing.

For the fronts of our cars 4.5 BS is what you need up front so that puts us needing a 2.25" adapter and after putting them on I can tell that is all that you can go with - cannot put aything narrower or it will rub the tierod end.

For the back there is more room - I am going to try to put 2" adapters if I use them again. Maybe even 1.7"I hope this helps.

Tom

Kennerz

Sorry tomclf,


9.5 divided in half is not 4.25, that would be on an 8.5in rim, the correct math is 4.75 for a 9.5 in width rim

Just didn't want anyone to make a misteak when using your reference #'s to buy rims.

tomclf

sorry - my mistake - I knew that - simple math. Thanks for the correction.

However - I can verify from installing the 9.5 width Z06 rims with 275 width tires that 2.25" on the adapter is an absolute must - any narrower and there will be rubbing issues with the tie rod end. I put the whole setup on my car and raised it up on the rack and looked at it with my own eyes - very little clearance - almost too little with the 2.25" adapter.

Hope this helps,

Tom

seanof30306

iTrader: (4)

Actually, that's not correct. The published rim width is measured from the INSIDE of one wheel lip to the other. When you measure backspacing, however, you measure from the OUTSIDE lip back to the mounting surface. To establish a wheel's centerline, you measure from the OUTSIDE of one wheel lip to the OUTSIDE of the other. This may not seem like much, but there is often as much as 3/4" to 1" difference between the published width of a wheel and the outside-outside width. Also, the lips are often of different thickness as well (the front lip is usually thicker).

There are 25.4mm in 1", so, to convert a +58mm backspace to inches, for example, you divide it by 24.5 to get 2.28" (about 2 1/4")

If you want to calculate the frontspacing of a wheel (how much the wheel sticks out), you first need to establish the centerline. If you don't have the actual wheel to measure, but you have the offset and backspacing, you subtract the offset from the backspace (if it's a + offset, as is the case with wheels for our cars) to establish the centerline. Then, you subtract the backspace from the centerline to get the frontspace. What most people don't realize is that the frontspace of wheels (how much they stick out) will vary widely among wheels with the same offset, depending upon their width,

For example, look at a 17 x 8.5" wheel with a +56mm offset and a 6.95" backspace. The + 56mm offset converts to 2.2" (56 / 25.4). Subtracting the 2.2" offset from the 6.95" backspace leaves a centerline of 4.75". Subtracting the 2.2" offset from the 4.75" centerline leaves a 2.55" frontspace. Also, notice that doubling the 4.75" centerline yields and actual, outside to outside lip width of 9.5", not the advertised 8.5".

an 18 x 10.5" with a +56mm offset and a 7.9" backspace has a very different frontspace, however, even though it has the same offset. Subtracting the 2.2" offset from the 7.9" backspace yields a centerline of 5.7". Subtracting the 2.2" offset from the centerline of 5.7" leaves a frontspace of 3.5", almost a full inch more than the 17 x 8.5" wheel with the same offset.

If you want to run a wider wheel on the rear than on the front, you'll (theoretically) need to have more +offset on the rear wheels than the front (if both the front and rear tracks are the same). What complicates things with our cars is that the front track is wider than the rear. Brake upgrades can make that dfference even greater. I plan on doing a C5 brake upgrade to my car, for example. Ed Miller says this will increase the track width by .3". I also plan on running a 4th gen rear. I believe this increases the rear track by 4" (I need to find out what that exact measurement is, by the way. Does anyone have that measurement for a 4th gen rearend?).

So, let's say you want to figure out what wheels to run on your car, and you don't have the wheels to test fit. The rears are a bit easier than the front, so we'll start there.

First you need to establish the track width. Take the wheels off the car and run a straight edge across the mounting surface of both of the rear brake hubs. Then, measure the distance between the two. That is your track width.

Next, take two pieces of string and tie a piece of dead weight to the bottom of each (bolt, nut, Mustang, etc.). Next tape them to the INSIDE lip of each wheelwell, letting them hang in the air (this is called a plumb bob, or a plumb drop). Measure the distance between the two strings to get the inner fender lip to inner fender
lip measurement. Subtract 1" from that measurement (you need at least 1/2" per side clearance between the fender lip and the tire to make sure it doesn't rub under extreme cornering). Hold on to that measurement.

Now, subtract the track widt from that measurement, then divide it by 2. This will give you the maximum frontspacing you can run without rubbing.

Done, right? Wrong. The sidewalls on your tires will "bow" out somewhat past the outer wheel lip. The taller the tire (generally), the greater that bow. You need to contact the manufacturer of the tires you plan to run to get the maximum (inflated) sidewall-to-sidewall width. You then divide that in half to get the TIRE'S centerline. The, you subtract the WHEEL'S offset from the tire's centerline to get the actual frontspacing of the inflated wheel and tire combo. Now you will know where the wheel will fit in the wheelwell.

tomclf

Wow! That is a lot of good information. Thanks for taking the time to type all of that out - that had to have taken some effort.

I know that for the front of my car - I have to have a 2.25 adapter to run a 17x9.5 Z06 rim with 56mm offset to clear the tie rod end which it barely does. I should have known that sooner but did not clearly understand enough to for see that. The wheel stuck out too far and I took them off and sent the adapters back.

I am trying to learn though. Sometimes even by trial and error.

Tom

seanof30306

iTrader: (4)

Thanks, dude, I'm going through the same process myself and have been gathering information, so I thought I'd post what I knew (so far).

One thing puzzles me, though. If your 17 x 9.5" wheels barely cleared the tie rod end and they stuck out too far, I don't get how other people are getting them to work. If they're barely clearing the tie rods now, they clearly can't be spaced further in.

tomclf

Check out this thread

https://www.thirdgen.org/techbb2/sho...hreadid=337074

They seem to be saying something similar.

When the car was on the rack and the suspension has hanging lose - the tie rod ends were about 1/4-1/8" away from the tire. I could not imagine getting any closer. When the car sits on the ground doesn't the tie rod end stay in the same position to the tire? If so, I cannot see how to move the wheel in any closer with out rubbing. If the position of the tie rod end moves away from the tire when the car is on the ground then there would be more room. If I am mistaken on this help me out. I would love to have more room to move the wheel in. Sitting flush with the fender lip is not what I want to do - I would like to tuck in a little so the tires never hit the fender under intensive driving.