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A tires salesman says that my sawtooth tires, which look like this

sawtooth tires

are the result of failed suspension. That makes no sense to me. Why would failed shock absorbers wear the tires this way?

These are relatively young tires (4 years since manufacturing, 3 years since install) with 50,000km on them. Unfortunately, they show unusual signs of early aging

aging tires

and so they need replacing anyway, but I'd like to solve any possible cause for the sawtoothing before replacing the tires.

In case your experience with this type of tire would help, these are Firestone Champion HR tires. The Firestone brand supposedly has a storied heritage, but with my experience I can safely say that any such heritage is strictly in the past.

Update/clarification

I'm looking for a mechanical (physical) explanation for the reason why any part of the suspension could result in sawtooth tires. Whether I'm doing 35mph/50kph inside the city or 65mph/110kph outside, the tires are rotating at a rapid rpm. It's a huge puzzle how suspension could result in this kind of wear. How would you explain it?

  • can you post more photos? preferably one spanning the entire width? – Martin Jul 21 '17 at 15:16
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    Tires wear unevenly because of alignment issues shake down the suspension and do a visual inspection. Get the alignment checked. – Ben Jul 21 '17 at 16:11
  • Alignment or balance issue. – Moab Jul 25 '17 at 0:15
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I've done hundreds of alignments and this pictured type of wear can begin very shortly after you have everything in order. DizzyFool may have moved his alignment enough to cause similar wear because of his track runs...your alignment is definitely off. There may still be a failed suspension component causing alignment issue ONLY while driving and under load(s). For instance, I ride a bicycle and it's perfect; I carry a passenger and the tires are deformed against the pavement; I ride with a passenger and wiggle my steering(like something is loose) - the tires look like yours. Ben has already given you the solution. Cheers!

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The advice the tyre person gave "failed suspension" is not limited to the shock absorber - there are several other joints, bushes and possibly arms depending on the design that could be at fault.

All need to be checked and it may be advisable to have an alignment carried out to find the issue if it is not obvious.

  • I think hard driving (or other driving that adds strain on tyres) can also cause this, case in point, my tyres look exactly like this. Before buying these new tyres, I replaced every bushing (some OEM, others polyurethane), tie rods, bearings, shock absorbers, and added bracing and bigger anti roll bars. I had an alignment done at the same time the tyres were fitted and after a few track sessions and country drives, the tyres appear this way. I never thought it was a safety issue but seeing this question is making me question that. It has passed its annual inspection (MOT in UK) with no issue. – DizzyFool Jul 25 '17 at 11:05

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