Piston Slap: This Group Must Somehow Form a Family Edition

Sajeev Mehta
by Sajeev Mehta

Eric writes:

I have a FWD car. One tire has a nail in it and probably can’t be repaired.


1a) If the replacement is the same model/size/brand tire, should I replace one tire or buy two?


1b) If one tire, should it go in the front right (to wear out the new tire faster, catch it up to the other 3) or rear (newer tires on back avoid oversteer)?

Same question as 1a and 1 b except:

2) if they don’t have the same model tire, and I am offered a different tread but same size/manufacturer/all season…

Lots of people get nails in one tire only, so hopefully your answer will get lots of Google hits! Thanks!

Sajeev writes:

You can get away with one, if the other three aren’t so old/worn they should be replaced anyway. I once had a nail through the sidewall (insert NSFW here) when I had about 25 percent tread left all around. My summer tires aren’t cheap, so I didn’t consider a cheap stop gap tire because I’d need a new set soon(er or later). That’s how I roll, so to speak.

For 1b, it also depends on the age of your other three tires. And the driving skills of the people who drive this car. If drivers are familiar with controlling oversteer and the current rear tires have 75 percent or more tread left, I would put that new tire on the front right. Actually I’d take it to the drag strip and do a parking brake-on burnout to shave that new tire down in a hurry. Hey, might as well make lemonade out of lemons, right?

My reasoning for question in a FWD car, differentials compensate for the speed differences (tire height and circumference between a new tire and a used one) between the left and right tire. This may not apply to AWD vehicles (or 4WD with locking hubs), and the owner’s manual is a great resource for that.

For question 2, get the closest quality and design to what you currently have. Same speed ratings, same basic mission: if you have three summer tires, winter tires or all seasons, keep the fourth tire on that same track.

Sajeev Mehta
Sajeev Mehta

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  • JTParts JTParts on Mar 29, 2009

    I plugged my own tires for years UNTIL I repaired a screw puncture dead center in BFG radial. A couple weeks later the tire came apart at speed 65+ MPH. Causing SUBSTANTIAL damage to the rear quarter panel, and my undergarments. In one moment the laws of Karma regained all I had saved over the years fixing my own. Nowadays I take all my flats to the tire shop and if they say it's a new tire, it's a new tire. On the FWD deal, I believe Sajeev broached this above, the differential in your car HAS to allow for variances in wheel speed from one side to the other, like when you go around a corner and the outside wheel has farther distance to travel. That's great in a limited situation like that, but when you have a speed differential all the time you are constantly wearing bearings and gears that are not designed to take that load. I see this all the time with the Tempa spare deal on the front of FWD cars. Any time you get a flat on the front of a FWD car you should move that tempa spare to the rear...

  • Matt.treiber Matt.treiber on Mar 30, 2009

    You didn't mention whether or not you have a full size spare and its condition. If it's still new, you can get away with only one new tire. Buy a new one and match it with the spare while putting the other tire on the spare wheel. And yes, only a nail through the tread can be replaced -- to close to the sidewall and you compromise the integrity of the tire. When I used to work at a tire store we were always on the look out for interesting flat tires. The best I saw was a open-end wrench that went in through the tread and came out of the sidewall. Way cool and we put it on display for customers.

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