The Stovebolt Site Forums The Shop Area Driveline How to identify 16.5 inch wheel

I have a weird shimmy in my 1950 3600 tow truck that I'm not entirely convinced is coming from the steering. I feel it more through the seat of my pants than through the steering wheel. I suspect the tires are out of round or something. It was up in the air this weekend while I was rebuilding the steering system, so I looked carefully at the wheels and tires. I couldn't see anything obviously wrong with the tires, which are 255/70/16 radials on standard dually deep dish wheels. But one of the rear wheels (passenger side, inner wheel) looks different than the others. The edge of the wheel was far less defined than the other wheels--there was less of a "step" from the wheel rim to the edge of the bead, and the outer lip is much more pronounced. Check out the photos--the first two are of the wheel in question, while the third photo shows what appears to be a normal 16-inch wheel mounted on the other side of the axle.

I did some looking and found a few photos and discussions about 16-inch tires on 16.5 inch wheels. Most of the discussion is about "don't do it!" and the accidents that people have heard/seen, but there weren't many posts saying it couldn't physically be done. I would think that it would be impossible to stretch a 16-inch tire an extra 1/2 inch (which, in terms of circumference, is more than 1.5 inches of stretching a steel-reinforced tire bead) but I think that's what's going on with my tire/wheel here. I think the moron who owned this truck was so cheap and such a hack that he figured out how to do it and risked life and limb to save a few pennies. What do you think? I don't know what a 16.5-inch wheel should look like.

It should be pretty easy to measure each wheel across the face with a pair of calipers - even homemade ones, and look for differences.

Wheels have stamped dimensions on them, usually on the outside, look carefully. Hold a known wheel(dismounted) next to the suspect wheel, should be able to notice any difference. Take suspect tire and wheel off and drive?

Ed

Measuring was actually the first thing I did. The wheels are within about 3/16" of each other in terms of overall diameter. That's not conclusive either way. The outer rim doesn't really determine wheel diameter, it's the inner rim where the tire is seated that makes a difference. Unfortunately, there's no way to accurately get a measurement without removing the tire. I was hoping that someone who has seen more 16.5 inch rims than I have would recognize it right away. I've attached photos of a wheel I found on the internet that looks very much like my wheel and it's confirmed as a 16.5. It just looks different--the shape of the outer rim is much flatter and there's a less pronounced corner where the bead seats.

The fact that the two wheels are clearly different one measures larger than the other (even if it isn't where proper rim diameter is measured) would be enough evidence for me. to remove the suspected wheel and tire and measure it properly. Better safe than sorry.

Even if it is a 16" rim my sense of symmetry would compel me to remove it and find a rim that matched the other three.

Agreed. I'm already searching for a replacement wheel, perhaps even a pair just for, as you say, symmetry's sake. New tires are probably on the list, too. An expense I didn't anticipate but I safety matters.

Hopefully this will also cure my shimmy. Thanks for all the advice!

All those wheels in your first set of pictures have the "safety notch" that the 16" tire bead snaps over to lock it to the rim as it's inflated. A 16.5" wheel is for tubeless tires only, and it has a very pronounced taper just inboard of the flange, and no safety bump. The only way I've ever seen a wheel/tire mismatch even get inflated in the first place was a 16" tire WITH A TUBE IN IT put on a 16.5 wheel, and it blew off the rim and nearly tore the guy's arm off who was inflating it. Even if one got inflated successfully like that, it wouldn't make it 5 miles on the road.
Jerry

Your shimmy could be from a bent rim...jack the wheels off the ground and set a brick or tool box next to the tire and spin it while watching the gap between them, if it's bent you'll see it...

Mike B

And don't forget the drive shaft/s and mid-ship bearing, it doesn't take much of being out of balance to feel it in the seat.

I would be surprised if a 16 will fit on a 16.5 rim, but I am sure it has been done with success being all over the place. I thought all 16.5 wheels were split rim requiring a tube? Maybe not.

I recently had a shake I could not figure out. I jacked the rear of my truck (03 Ram with a 22.5" conversion) and brought the tires up to speed. You could clearly see one tire was out of round. Went to the tire shop with other tires I had and they showed me it was not mounted straight on the wheel. It was offset a little on the bead causing the issue. They said with heavy OTR trucks it would pound it into place, but with mine it needed to be paid attention to. They got it on straight and all was good.

16.5" tubeless have been around for some time now. Our old race trailer has 6 on it with a same tire diameter 16" spare. Radials, of all things! Hard to get tire, though. So I was collecting 8 lug, 16" rims to get away from the 16.5's. Then we upgraded to a new trailer.

Mark, the 16.5's are supposed to be a "same height" swap for a 15" tube type, like a big rig 20" and a 22.5., or a 22 and a 24.5, etc. The only real advantage to a tapered bead tubeless tire is it's easier to do a roadside tire change than the corresponding height tube type. Now, getting it inflated- - - - -that's another kettle of fish! We're not supposed to mention acetylene or starting fluid, right?
Jerry

I've never tried either of those , but how about the bands that you strap around the tire to get the beads to spread apart? Haven't tried that either. A ratchet strap might work.

Backin my old Jeep and dune buggy days, we would use a tube to seat one side, remove the tube and get the other side seated, worked well on fat tires!
.

Ed

I've used far more starting fluid inflating tires on the side of the road than I ever used for getting cold engines fired up. That's just the way it was done when doing tire changes on big rigs. Yes, there is a somewhat "safe" method which involves some pretty coordinated use of a clip-on inflator chuck and a ball valve in the air hose, and a trail of fluid from the air hose operator to the tire. It's definitely an acquired skill that can involve some singed eyebrows during the learning curve!

In these days of lacy drawer snowflakes and OSHA regulations, the "Cheetah" tire inflator tank is the way to go!

www.ebay.com/itm/272206797861?

Jerry

I've been with the same company going on 38 years now. Acetylene or starting fluid were never taught nor approved as a tire mounting method. Yeah, I know. No fun. Safety first!

I've used bands with some success but not always. Ratchet straps will do the same thing. Before Cheeta's, a tub of near solid tire lube would be your friend. Fill that upper bead with as much as you could and when the tire bead would seat, scoop all the goo off and put it back in the bucket. Surprisingly, not much would end up inside the tire! But extremely messy.

I'd say I found the source of my shimmy and it is indeed that weird wheel that seems to be having trouble retaining the tire.

www.youtube.com/watch?v=5n4_vewlcxM

The way to do keep the video from embedding is to clip the https:// off the front of the web address. Then it's just a clickable link to view.

I've reported it to Sweet so he can deal with it if Matt doesn't get the chance.

As Kevin said, there is no need for the hxxps..// Just start the link with www.

Sweet is out of pocket. I got the "flagged" post. That's the best way if something is urgent in a forum and the Moderator (see list on the left) is not on-line.

I did the Kevin "switch" with removing the https:// ....... works.

Good job all.

Good job on finding your shimmy issue!