I recently had a customer come back with the complaint that around 110km/hr the vehicle is very shaky after installing winter tires.

I retorqued all four tires and none of the lugs moved. Air pressure was fine and I examined the tires for balancing weights or marks where a balancing weight may have fallen off. All of them had weights and I couldn't find any places where a weight may have come off.

Customer states they had just bought the tires (used), already mounted on rims.

I know it's customary in the shop I work in (and others) to give the tire a good kick or a whack with another tire if it's seized on.

Is it possible hitting the tire with a reasonable amount of force could throw out alignment? I would assume it would only do so in an already weakened vehicle. If not - are there any other potential sources of the shake? I told the customer to go get the tires checked for balance, as that was the only possible culprit I could think of.

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    If they bought the tires used and already on rims, who knows what state the wheel balance was in? The only way to find out is put them on a balancing machine. If they had worn unevenly for some reason, the original weights would be wrong in any case. Maybe the customer's vehicle is just more sensitive to unbalance than whatever they were on before they were sold. Or maybe they were sold because they never ran smoothly! – alephzero Nov 12 '18 at 17:16
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    Did you actually check the balance of each tire? Just because they have weights doesn't mean it was done right. – GdD Nov 12 '18 at 17:17
  • @GdD the OP "told the customer to get the balance checked" so presumably he doesn't have a balancing machine. – alephzero Nov 12 '18 at 17:20
  • Correct - don't have the tools to do it. I think it's the best hunch I was just curious to know if I may have missed something. @GdD Good call on the "reason for selling" – Brydon Gibson Nov 12 '18 at 17:21
  • It was @alephzro who mentioned the bit about selling. – GdD Nov 12 '18 at 22:16

If the car shake at speed higher than 105 km/h it's the balance of rear tires or maybe bent rear wheel rim. If shaking occurs when going 50-100 km/h it's the front tires/wheels problem.

  • Interesting - have you got any references to back this up, as I've not heard it before? – Nick C Nov 13 '18 at 10:06
  • @NickC sadly no. I studied this at physics class and actually saw it myself a few times on few cars(including mine). I'm sure if you google it hard enough you will find some videos/tests whatever. – AsenM Nov 13 '18 at 10:28
  • @NickC If you don't find any info you can test this yourself pretty easy. Mark your car balance weight with a pen on your rim and move them on some random spot on front tires. Then go for a ride and see at what speed you will get vibrations, then put the weight back on the marked(original) spot, repeat this with back tires. – AsenM Nov 13 '18 at 10:31

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