Question regarding wheels.

[StangRay]

Hi all,

I have a question regarding aftermarket wheels. I have selected a set of Ford performance wheels for my winter tires that will go on my Mach 1 and I am concerned about the offset from the center of the rim. I asked the Ford Performance guy about this at a car show and he said he had no idea. And he was right, he was totaly clueless about anything on a Mach 1 or wheel specifications.

Here is my concern: Wheels are made with the part that bolts to the axle hub (what I will call the "wheel" hub section) to be a particular distance from the outside edge (bead) of the rim. It may not be perfectly centered. Each rim has a specification for the width of the bead. For the most part we are looking at 8" widths (bead to bead). Therefore, if the distance from the outside bead to the hub section is 3 inches, and the total width of the bead area is 8 inches, then we know that the distance from the wheel hub to the inside bead is 5 inches. This also tells us that the hub of the wheel is not centered to the wheel width. This causes the center of the wheel to be inside the axle "center." This has a big effect on the turning angle as the tire comes off of center to go left or right. If the offset is not identical to the factory installed wheels, then the alignment will be off. I remember this problem with chrome reverse wheels in the old days and I was taught in alignment school to look out for this with wheels from junk yards. Just because they bolt up, doesn't mean that they are the right rim for the car. This mismatching can drive an alignment guy nuts trying to set caster. (I know, most new cars have no adjustment for caster these days, that is what has me concerned about the wheels) I do not want to have to buy caster plates. I want it easy by getting the correct wheel size and type.

When I looked at the wheels in the sizes that I could use for my Mach 1 at the car show, I saw definite differences in hub offsets. This concerned me because I do not want to have to try to hack the alignment to make the steering perform well on turns.

So, what I am really trying to get here is some information from you guys that are familier with this issue. Does anybody know the offset with our stock Mach 1 wheels?

Also, can somebody please bring me up to speed with the correct terminology related to this stuff so I can have an educated conversation with the wheel guys? It seems that what I describe should relate to specifications for the wheel and all I need to do is to be sure to check the specification before I order it. I doubt that anybody has the wheel specs for the Mach 1, but it would give me a jump start if I could get the terminology correct as a start.

One other question; I know that we need 17" wheels at a minimum for clearence of the 13" brake rotors. But will all 17" rims clear? Is there a specification for that as well?

Thanks.

[falcongtho3]

I'm going to give this one the best shot I can . I have been in the wheel business for a number of years. (This # to remain secret due to the fact that I am older than all Mustangs.)
1) You mention "Ford performance wheels ". You don't specify which. All the ones in the SVT/performance/accessory catalogs that fit Mustangs are Mustang-specific. These (17" and larger)all should do what you want,since they are designed for the Mustang.
2)You mentioned clueless people pedaling wheels. This is common, most people that buy wheels are clueless about the things that you are concerned with. So, if they fit, good. Mustangs are considered mid-offset in wheel application, but will take high-offset(front wheel drive) wheels with no/few mods. Many chrome/18"+ size rims you see on 'Stangs are not sorrect, they just look "bad", at least to them.
3)Offset is the relationship of the "hub face" of the outer lip of the rim. (Remember this) This is measured in "mm", either positive(think front wheel drive), mid (Mustang, Camaro,Firebird), or negative (think deep dish/pick up truck). Deeper dish wheels will also work, but that is when you have outer fender clearance problems, as opposed to possible inner fender clearance problems with pos. o/s wheels. Also if you add the rear back spacing(hub face to rear outer lip) and the front spacing(hub face to front outer lip) the measurement should be 1/2 inch more than the wheels advertised width. The width is measured from where the bead seats to the rim, not overall width.
4) Wheels can be hub-centered or lug centered. All factory wheels fit tightly to the axle/spindle hub and that's how they are centered so they spin true. Most aftermarket wheels are lug-centered and rely on the lug nuts to center the wheels. Sometimes this works, but not always. This will result in vibration and could result in pre-mature mechanical wear. Most aftermarket wheels can have hub-centric rings added to them (at little or no cost to the consumer) which will hub-center the wheels, and they will spin true.
5)It is near impossible to get aftermarket wheels that are the exact offset of the factory ones, get as close as possible. Then have the alignment checked. Exact wheels are not cost effective to the industry, and those wheels that can be 'custom ordered' like Boyd's or Billet Specialties are more expensive than off the shelf wheels, they are polished alum. as opposed to chrome or painted finish, and do take weeks to have made and shipped.
6) I hope this helps and you didn't fall asleep...zzzzzzz

[StangRay]

This is just what I was looking for!

Two more questions: What does 4.5" bolt circle and 5.72" backspacing mean?

I think that the 4.5" means the circumference of something. The hub hole? Is it the distance from the center of hub to the center of the lug?

As for the 5.72" backspacing, is this what you call the "rear" back spacing? This seems to make sense to me.

If my assumptions are correct, then the wheel is 8 - 5.72 = 2.28" front space offset (not considering the 1/2 inch that might be included inthe 5.72" specs of the wheel). Am I getting close?

Do they factor in the 1/2 inch extra for the lip or just base it on a nominal 8"? Would I be more correct to do it this way: 8.5 - 5.72 = 2.78" front space offset?

My information is being taken from the Ford Racing Performance Parts booklet. Do these rims have hub centering since they are built by Ford?

Thanks for the info! Interesting stuff!

[falcongtho3]

Whew! Tough class! The 'bolt circle' or bolt pattern is an imaginary circle that passes through the center of all of the studs on the wheel or hub. This is easy to measure on a 4, 6 or 8 lug pattern since the studs or lug holes are directly opposite each other. On 3, 5 and 7 lug patterns not so easy. There is a special bolt hole measuring device that most wheel sellers should have that is simple to use, but goofy to look at. The easilest way for someone to do this at homw is not real easy, since there is only 1/4 inch variation on most domestic patterns. The easiest way is to get an acurate measure from the exact center of the hub to the center of any stud or lug hole, then double it. All 5 lug Mustangs are 5 on 4 1/2 inch lug pattern, ever since 64 1/2.
The backspacking of the wheel (or front spacing) measurement does include the distance to the outside (or face) of the wheel. The measurement of the width of the wheel does not. So if you measure 5 1/4 backspacing on an 8 inch wide wheel, you can safely assume a 3 1/4 front spacing. This takes into account the approximate 1/2 extra width from the inner bead seat to the inner or outer face of the wheel. (1/4 each side)
Hope this helps. ( Now, wake up! I hear you sleeping out there!)

[socalmach1]

HUH?

[falcongtho3]

Huh, what? If you've got a qusetion please ask. I know this can get involved/confusing. Just trying to help.:THUMBSUP:

[Azure Mach]

:MADNOEL: Isn't there a posting limit of 500 words or less?:MADNOEL:

:SMASH:
:SMASH:
:SMASH:

[R code]

Stangray, regarding your cars alignment with the use of different offset wheels.
Changing the wheel offset or backspacing will not affect the alignment at all. Caster angle will remain constant since this is actually a measurement taken at the spindle, not the wheel or tire. What does occur when large negative or posititive offset wheels are installed is that the center contact patch of the tire tread is no longer inline with the turning axis of the lower ball joint and upper ball joint or strut bearing. With a large negative offset wheel, (wheel sticking out from the car) the wheel makes a much faster arc when turning. As you stated THIS is what the alignment tech needs to watch for. When the tech is taking a caster sweep, he thinks he is turning the wheels 15 degrees left and 15 degrees right, but actually with the offset wheels he is only maybe going 10 degrees at the spindle. This is where the problem can occur. The best thing to do would be align the vehicle with with the factory wheels and then install your aftermarket wheels if the offset is different. However I think you would have to have some pretty off the wall wheels in order to get some funky alignment readings. You would well run into tire clearance problems on a late model mustang first.

[02mach1]

Here's what I put on my mach1:CHEERS:

[R code]

Now that's the Magnum 500 wheel the our Mach 1's should come with from the factory! I think it has a much more of the earlier type look to it. Very nice.:THUMBSUP:

[02mach1]

Your right:D

[Mach Won]

wow who makes those wheels- they should have put those on!!

[AZDave]

Try:
http://www.nostalgiawheel.com/
or
http://www.wheelvintiques.com/billet.html

[02mach1]

www.classic-designconcepts.com/ have those wheels;) too

[03mach1]

Here is some useful info...http://www.tirerack.com has a ton of info.

Measuring Wheel Stud Size - Bolt Pattern
http://www.tirerack.com/wheels/tech/boltpatt.htm

Measuring Backspacing/Offset
http://www.tirerack.com/wheels/tech/offset.htm


Hope this helps! :)