Hi Forum !
Last fall I had new P190-60R15 Dunlops put on my 15x7 rims (2002 Mazda Protege DX 5speed manual tranny). I told the tire people that do occasional turnpike driving and wanted them to be smooth at 70-80mph. I also wanted the chrome-over-rubber valves instead of the plain black ones. They said they put their best guy on it for me (for $125 mount and balance they should have).
The car felt smooth around town but I didn't drive the pike for a month past the install. Then I had a turnpike trip to take. At 68mph I started to feel the shake that wasn't there before. at 72mph it was very noticeable. For the next six or so months I just kept it down to 68 figuring I'd take it back for a re-balance, but never had time for it.
About a month ago, before the same turnpike trip, I checked the pressure and they needed a couple pounds of air. This time I went around and took off all the valve caps before bringing out the portable air tank. I then noticed that although all the caps looked like chrome metal, two were actually plastic, and were noticeably lighter (almost weightless) than the other two which were metal. So I 'm thinking, "I bet they don't have these valve caps on when they spin balance the tires." So I left all the valve caps off the tires for the turnpike run. Guess what? No shaking anymore above 68mph. So I bought 4 plain black plastic caps, put them on, and have had joy ever since.
Today while waiting for some computer stuff to fully bake, I have time to to make this post. I made a simple balance beam from a wood ruler on top of a horizontal pencil. I put the valve cap on one end of the ruler and found that a new penny (ie. 2.5 grams) balances with the metal cap on the other end of the ruler.
So the question is: Am I having some delusional observation about the metal caps throwing my tire balance job off? Seems to me that 2.5 grams out there near the O.D. of the tire, at 70mph, would be enough to induce a vibration.
Also seems to me that if one were really picky, and absolutely had to have metal valve caps for some reason, that they'd want the tires balanced with those caps screwed down on the valves.
I look forward to your comments (and ribbing
Regards,
Brcobrem
Last fall I had new P190-60R15 Dunlops put on my 15x7 rims (2002 Mazda Protege DX 5speed manual tranny). I told the tire people that do occasional turnpike driving and wanted them to be smooth at 70-80mph. I also wanted the chrome-over-rubber valves instead of the plain black ones. They said they put their best guy on it for me (for $125 mount and balance they should have).
The car felt smooth around town but I didn't drive the pike for a month past the install. Then I had a turnpike trip to take. At 68mph I started to feel the shake that wasn't there before. at 72mph it was very noticeable. For the next six or so months I just kept it down to 68 figuring I'd take it back for a re-balance, but never had time for it.
About a month ago, before the same turnpike trip, I checked the pressure and they needed a couple pounds of air. This time I went around and took off all the valve caps before bringing out the portable air tank. I then noticed that although all the caps looked like chrome metal, two were actually plastic, and were noticeably lighter (almost weightless) than the other two which were metal. So I 'm thinking, "I bet they don't have these valve caps on when they spin balance the tires." So I left all the valve caps off the tires for the turnpike run. Guess what? No shaking anymore above 68mph. So I bought 4 plain black plastic caps, put them on, and have had joy ever since.
Today while waiting for some computer stuff to fully bake, I have time to to make this post. I made a simple balance beam from a wood ruler on top of a horizontal pencil. I put the valve cap on one end of the ruler and found that a new penny (ie. 2.5 grams) balances with the metal cap on the other end of the ruler.
So the question is: Am I having some delusional observation about the metal caps throwing my tire balance job off? Seems to me that 2.5 grams out there near the O.D. of the tire, at 70mph, would be enough to induce a vibration.
Also seems to me that if one were really picky, and absolutely had to have metal valve caps for some reason, that they'd want the tires balanced with those caps screwed down on the valves.
I look forward to your comments (and ribbing
Regards,
Brcobrem
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