Bias ply tires have the tread rubber installed on the carcass before it is inflated. If the raw rubber tread was cut too long or if the tread rubber was still warm from the extruder when applied there could be an excess of rubber at the splice which woud cause the tire to have an excessively thick layer of rubber under the tread. The tire would require a significant amount of weight to balance and often required milling to true it. Radial tire carcasses are expanded when the tread rubber is applied and the builder has very little tolerance on tread length.
Does anyone still sell bias ply tires? For passenger cars that is…
I haven’t seen any since the 60s.
Coker Tire sells bias ply for the collector car people who want to be as original as possible.
They do, but if there’s something in this thread that suggests these are bias ply tires I missed it.
Bias plys went out in the late-'70s. My '72 Vega came with them, and I upgraded to radials in about '74 to try to smooth the ride out. But bias ply tires were still commonplace in '74.
I agree . . . I seriously doubt OP’s car has bias ply tires
But I’d still like to see pictures of the tires. All we’re really doing is speculating
I don’t have a camera or photo-capable phone right now, so no pictures.
The way I determined out of roundness was to jack up the vehicle (2007 Chrysler Town and Country) and rotate the tire. I then lowered the vehicle bit by bit until the tire touched the flat concrete garage floor during part but not all of its rotation. I then eyeballed the gap between tire and floor. The gaps, where present, were of various sizes. The larger ones looked to be abut 1/8 inch.
I was not so much interested in the amount of out of roundness as I was in finding out whether out of roundness was present. And it is, especially the right front tire. It was while riding in the passenger seat that I became more aware of a sensation of up-and-down unevenness.
I will have to remove the wheel cover and give a close look to see if there appears to be unevenness in the mating of the tire sidewall to the wheel. At that time I will be able to rotate the tire again and look for out of roundness in the wheel, too.
I may ask around for road force balancing, but only after I have found out and done what I can at home.
Wanting a project and to save some money? For sure! Now that I am retired and on reduced income, I appreciate even more the ability to DIY! And I thank all of you who have contributed to this conversation.
Good for you. Saving $100 is like earning $140, then paying $40 in taxes. So if you do this yourself, you really saved $140, and what’s more, no boss monitoring your whereabouts … lol . .
George, you are so right. You remind me of my dad.
Come to think of it, I remind me of my dad more and more nowadays!
I brought up bias ply tires because out of round was more common on them than radials.
After reading @shanonia’s explanation of how the out of round was measured I’m not certain that it’s significant. If the tire in question is inspected closely and has no significant balance weights located 180* from the high spot yet the tire shows no indication of being out of balance there is likely no problem with the tire. If truly out of round the tire would also be out of balance.
Sounds to me like somebody did an incompetent job of balancing the rims . . . sadly, this is extremely common
I’ve known SO many guys, the only thing they care about is if the machine shows zeros. Never mind if it’s obviously wobbling side to side or up and down. Never mind if you’ve got 4 o 5 weights on the rim, totalling 12 ounces or more . . . 
I actually tried talking to some of the guys a few times, but the response was not encouraging. While I was not threatened with bodily harm, the message was clear: “Don’t talk to me about balancing rims, because I simply don’t care. And I’m not interested in learning, either. Go away.”
db4690,
While I appreciate that you understand what may be going on relative to balancing a tire, I can not tell you how many times I have been told by self appointed experts what the “correct” way to [insert procedure]. It is so common that the average guy learns not to listen to anyone giving out advice.
LOL, beyond that point, there’s a whole lot of people out there who consider themselves an “expert” in an area after ten minutes of training. There’s also the illusion that ten years of doing the same thing every day equals ten years of experience rather than ten minutes of experience ten years over. 
All I know is this . . .
When those other guys balance rims . . . some of them do not EVER balance, even when replacing tires and/or rims . . . more often than not, the rims have a LOT of weight, and a LOT of weights. And the steering wheel is shaking. It’s sometimes so bad, that the entire vehicle is shaking and vibrating.
Here’s the amazing thing . . . a few months ago, a repair order was given to me “Customer complains about vibration at highway speed”
A particular guy drove the truck, FELT the vibration, SAW me fix it by properly balancing the rims, FELT that it was normal because he drove it afterwards. And he’s one of the guys that either doesn’t balance rims at all, or does a lousy job of it
Some guys simply do NOT care, even if they KNOW they’re doing it incorrectly
In all other respects, he’s a great guy. He’s fast, he gets a lot of work done, but he doesn’t care about things which he considers “minor details”
How can ANYBODY think that 12 ounces . . . or more . . . of weights is normal and/or okay?
How can ANYBODY think that 5 weights per side is normal and/or okay?
At some point, you would think common sense would step in, but I suspect these guys simply don’t care.
I welcome advice, because even though I consider myself a pretty good mechanic, I’m not smug enough to think that I know everything. And I know there’s plenty of people that know better ways to do things
I feel it’s worthwhile to listen to somebody’s advice
It does NOT mean you have to take it 
db4690: You are so right on. We mere mortals can never learn everything. I was raised with the work ethic of doing the best job you are capable of doing. If it is not good enough you need to learn how to do it better. I have known and worked with the ones who don’t worry about the minor details and have no desire to improve. I have always called that “aspiring to mediocrity”.
I don’t have co-workers that are incapable of balancing tires, we don’t have come-backs for tire balancing. Also I do not see balancing problems coming in from tire shops. I don’t believe this is an industry wide problem.
I also don’t think there is an “industry wide problem” . . . I don’t think I or anybody suggested it was
I happen to think that incompetent and/or lazy individuals can be found just about everywhere, in just about every business, shop, etc.
I think a lot of people are unwilling to admit they don’t know something because they are afraid of being seen as stupid. In extreme cases they may fear losing their job if they do it often enough. I find this especially prevalent among engineers.
jtsanders said: " … I find this especially prevalent among MEN. …" FIFY
" I find this especially prevalent among engineers."
Respectfully, I cannot agree with this statement. Engineers become engineers due to an insatiable thirst for knowledge, and while I have worked with engineers that had an excess of arrogance, most automatically assume there’s a whole lot to learn on a new issue and relish the adventure. Most welcome new knowledge with open arms. Challenging new knowledge is common, as it’s part of understanding it, but the resultant debate is welcome with open arms.
Having spent 23 years in the manufacturing industry (most as an engineer and manager), and another 17 years in academia, I’ve personally found liberal arts personnel (especially the pseudo-scientists) to be far more likely to believe they already know all the answers than engineers, physicists, mathematicians, and other technical people. That’s not to suggest that most of the people in the former categories aren’t good people (most are), just a summary of my own experiences.
Nothing wrong with saying “Thanks for showing me how to do it the right way.”
I wouldn’t think somebody was stupid if they said that. I would think they’re grateful
When I mess up, and somebody shows me the right way to do things, I’m less likely to make the same mistake again. In other words, I learned something, and I’m now better able to do my job
Better to ask how to do something, and be shown how to do it correctly . . . versus being afraid to ask, and have it come back, and the customer is really upset. Now you may be working for free to correct the mistake. The shop may have to throw more parts at the car, to fix it correctly the second time. That’s assuming they even let you correct your own mistake. They may just give it to somebody else to repair, and backflag you. And the business may lose that customer in the end, anyways
Clearly, this is not restricted to automotive