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Shawn Blyler
06-27-2015, 01:37 AM
I just had four new BF Goodrich Silvertown H78-15 bias ply tires put on my car a few weeks ago. The tire shop is a block and a half away from me, and it was raining that day, so I just drove the car home and put it away. I finally took it out for a drive today (it finally stopped raining for once). I know that bias ply tires need a while to warm up to get rid of flat spots from sitting, so I drove it around town a few times before I took it out on the road. It vibrates terrribly, to the point that it actually unlatched the hood--I had to pull off the road and close it. I never went over 45mph.

When they balanced the tires, they said there was one that they had alot of trouble with and it took ALOT of weight. They also said that all the tires looked like they were out of round when they were balancing them. The tires were all spun balanced. This shop has been around a long time, and the three brothers that own it have been doing this since the early 60's, so they are not inexperienced young people. I will say that they put all of the weight on the back sides of the rims, as they didn't have Cadillac wheel weights--they threw them out a few years ago!!

My question is this: How can brand new tires be out of round? What do you do if you have one tire that will not balance correctly? If I purchase Cadillac wheel weights and have them balanced again, would it possibly make a difference having weight on the front of the rims AND the back?

I never had this problem with the radials that were on there, it drove smooth and vibration free. I would have thought if I had a bent rim or something, it would have shown up then. I am really hoping that I didn't just spent a bunch of money on tires that I cannot use. I certainly cannot drive the car like it is now. Any ideas, anyone? Thanks for your time, Shawn

Peter Grave
06-27-2015, 09:02 AM
I think you have got tires that are defective from the manufacturer.Many years ago (perhaps 30) I got a set of Dunlaps bias type almost the same movie you are saying. The tires were just defective from a bad run they took them back supplied another set end of problem. Any time you have to load a tire up with lots of weights its usually not made right. I do not think the weights being on the inside is an issue. I know fanatics who have the weights in the inside of their big $$$ wheels so the outer edge does not get scratched. Perhaps those with more knowledge than I can comment on this. I think your tire installers are correct.

John ED Renstrom
06-27-2015, 10:26 AM
if you just have one tire that used a lot of weight you might try marking the tire at the valve stem and have them rotate the tire 180 and rebalance it. if it still takes a lot of weight then call the supply house you got it from tell them what you did and ask for a replacement tire.

check for a bent wheel also. it happens with the power equipment. you might explain your problem to the tire shop. now just because there is a lot of weight on the tire doesn't mean it will bounce balanced is balanced. my bet is they missed the mark on all 4 of them. your bias ply will take a little more weight then a radial to balance but usually under 6 oz.

I have the same tires on my 72. the round out normally only takes a block or two. there is some distortion when they are stacked and shipped. you may have gotten the bottom of the stack set. rebalancing them after they have been on the car and driven a little may be necessary. it might account for the excess of weight on the one tire. but my guess still is that a wheel is bent. it's the only thing that would account for that violent a shake.

Larry Sears
06-27-2015, 03:29 PM
Bias ply tires appear out of round when on a balancing wheel compared to radial tires. Your tire people should of known that. It sounds to me like one tires wasn't balanced correctly or it could be a bad tire but I'll bet if they were rebalanced it would solve the problem. Doing a "static" balance is not as good as a regular balance with weights on both sides but it shouldn't make that much of a difference because the car is heavy. If you want a correct balance you will need to find some Cadillac style weights because I'm sure you don't want to drive around with your hubcaps off. Although, the tire with all the weights you could take it back and have them balance it on both sides leave the cap off and drive it and see if the problem is fixed, then find some Cadillac weights!