How much vertical&lateral clearance to allow?

[LS1_78Bandit]

This was sort've buried at the end of my "wheels for 78 t/a" thread. I thought it might help to pull it out to its own topic.

How much leeway should I leave for movement both laterally and vertically?

I just spent about 4 hours pulling my wheels off and measuring things in just about every way imaginable. Now I need to turn that info into "what to get".

I think the answer is going to end up being the 10.5". On the left rear, my total clearance from the shocks to the inside of the fender lip is 11.5". That would mean a tolerance of about 0.25" on either side of the wheel unless I either roll the fender lip or assume that the body will not come down far enough for the outside fender to be an issue. With my current suspension that's a reasonable bet, but with all the new suspension parts going in, it's possible it will be an issue.

And I'm glad I followed everyone's advice and measured both sides. I had more like 12.5" of clearance on the right side. I think that the left side fender was replaced during the restoration which might explain the difference - or it could just be "situation normal".

UPDATE: I was talking to the salesman that's selling me the rims and he was saying that there is a 0.75" lip on either side, so the true width of a 10.5" rim is 12". Does this make sense?? I thought that when a rim was listed as "17x10.5" that the width was actually 10.5". If the true width is actually 12", I'm not sure I can even fit the 10.5" rim ... Harumph.

[astroracer]

The "width" of the rim is measured across the inside seats for the tire bead. An aluminum, 10" wide rim, will actually be closer to 11" total across the outside of the beads. Aluminum and steel will be different because the rims are held to industry standard dims on the inside where it is important, so a thinner steel rim will give a touch more clearance.
Rim width is less important to fender or frame clearance then tire cross-section though. The tire will usually protrude (bulge) past the rim unless you have a narrow tire on a wide rim (not recommended...). The tire bulge will also change with rim width. A 255 on an 8" rim will have more bulge then one mounted on a 10" rim but this is usually a moot point as the extra width also pushes the tire sidewall farther out.
I TRY to maintain at least 3/4's of an inch to the fender and a little more to the frame although my truck is running at about 1/4" to the fender and I have no rubbing problems at all.
Mark

[astroracer]

The "width" of the rim is measured across the inside seats for the tire bead. An aluminum, 10" wide rim, will actually be closer to 11" total across the outside of the beads. Aluminum and steel will be different because the rims are held to industry standard dims on the inside where it is important, so a thinner steel rim will give a touch more clearance.
Rim width is less important to fender or frame clearance then tire cross-section though. The tire will usually protrude (bulge) past the rim unless you have a narrow tire on a wide rim (not recommended...). The tire bulge will also change with rim width. A 255 on an 8" rim will have more bulge then one mounted on a 10" rim but this is usually a moot point as the extra width also pushes the tire sidewall farther out.
I TRY to maintain at least 3/4's of an inch to the fender and a little more to the frame although my truck is running at about 1/4" to the fender and I have no rubbing problems at all.
Mark

[LS1_78Bandit]

OK, now I'm completely befuddled.

I had been planning on a 17x10.5 because that would give me the option of either running 315/35/17's (which have a rim width range of 10.5-12") or 285/40/17's (which have a rim width range of 9.5-11"). But if the 17x10.5" rim is actually 12" wide, then the tire will *not* extend further than the rim because a 285 tire is only 11.2".

And on the front I was planning 17x9.5 because that would give me the option of either running 275/40/17's (rim width range 9-11") or 255/45/17's (rim width range 8-9.5"). But if the 17x9.5 is actually 11" wide, then again the tire will not extend beyond the rim because a 275 tire is only 10.8", and the 255 would definitely be a problem because it's only 10" wide.

So would I need to go to 17x10 and 17x9? Or is there some subtlety I'm missing?

[HILROD]

The rim would be 10.5 inches on the inner flange where the tire mounts, but the lips are wider making it 12 inches wide. All rims will measure that way but those are a little wider lip than most. FRANK

[USAZR1]

I've never seen a 10.5" wheel measure 12",outside to outside. :hmm:

[astroracer]

Here is a typical wheel cross-section. You will see the advertised wheel "width" is measured to the inside of the the beads. TOTAL wheel width is measured across the outside of the beads and will vary from wheel to wheel due to material and design differences. Most any tire will bulge past the bead, making the tire the widest part of the assembly.

https://static1.pt-content.com/images/noimg.gif