Dear Car Talk:
I have a 2022 Hyundai Santa Fe Hybrid AWD with 43,000 miles on it. On day one of a four-day drive from Maine to Texas, I developed a slow leak in one of my tires, losing about 15 psi every 100 miles.
After limping into our first overnight stop in Pennsylvania, I found a large nail in the tire. The next day, Sunday morning of a long weekend, I went to a chain tire store to get my tire repaired.
I was told that it was not repairable. And since my tires’ tread depth was already pretty low, and I had an all-wheel-drive car, I was told I had to replace all four tires. Needing to get from Pennsylvania to Tennessee on day two of our trip, I didn’t argue and bought four tires.
Arriving in Tennessee that night, I started to wonder if I may have been ripped off. Did the tire store advice seem reasonable or should I chalk it up as a lesson learned? — Jack
I don’t know whether your tire was repairable or not. If the nail was on or near the sidewall or the hole was too big, they may have been 100% right that it was not safe to repair it. But in terms of recommending four new tires, that was the right call.
When you have an all-wheel-drive car, you don’t want to have one wheel larger (or smaller) than the other three. And if you had one tire with zero miles on it, and three tires with 43,000 miles on them, that’s exactly what you’d have.
On an all-wheel-drive car, when the wheels have to turn at different speeds (like when you’re cornering), there’s a gearbox called a center differential that kicks in and manages all that. But if you have one tire that’s larger than your other three, that wheel would always be turning slower, and you’d force the center differential to operate continuously — even while driving straight ahead. And whatever you paid for four tires, it’s a fraction of what a center differential replacement would cost.
Some tire stores will “shave” a new tire for you to match the thread depth of your other tires for a healthy fee. But that only makes sense if other tires have lots of life left. I’m assuming these were your original tires, with 43,000 miles on them. And in that case, you were probably due for new tires soon anyway.
So, I think the guys you found were honest, Jack, and treated you well. And you’re now set for another 40,000 miles. On the other hand, that transmission rebuild they sold you …
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