My Sister destroyed a tire. The shop told her she must replace all of them. I call BS

[rickyd123]

She has a 2019 Ford Edge. It's AWD. She bought the tires about 2 years ago. She estimated she puts about 15,000 miles on the car a year. The side wall of the tire was damaged and the shop said it was not fixable.
She bought the tires at Costco. They told her that it would take them 10 days to 2 weeks to get the exact same tire.
She called Les Schwab. They told her She had to replace all 4 tires or she would damage her drive train.
I told her they were lying to her and go to Walmart and get a tire that's the same size as the others and drive on, but I consider myself a below average shade tree mechanic. She knows this and wants some reassurance.
The newest vehicle I've ever owned is a 1998 Ford F150, so I don't know anything about newer vehicles. I'm I right or I'm I wrong?

[maxwedge]

That has some merit in a awd vehicle. The rolling circumference of all 4 tires must be matched very closely, as well as tread pattern. If say the tires are 50% worn and one new tire is replaced based on the individual cars awd programming the different tire can cause the awd function not to work or set a warning lite. This happened on my Rav4 when one tire was replced.

[shorod]

I agree with Maxwedge here. You Edge shouldn't have any viscous couplings that could overheat, but the traction control system may not be happy about the different. If there's 50k miles on the existing tires, there's a really good chance the tread is at least halfway down from new. And replacing 4 tires is likely to be less that just about any driveline damage that might occur from mismatched tires.

I must commend you though on providing pretty much all the details that help make an educated response. You did a great job of putting good detail in a concise post!

-Rod

[RidingOnRailz]

Even 2-3mm of a difference in tread depth?

(RidingOnRailz rubbing thumb and fingers of one hand together..$$!)

[maxwedge]

Maybe not, maybe so. You wouldn’t know till drove it and either engaged awd or if it was full time awd, and what happens.

[Stealthee]

AWD systems are finicky. Not the same car but my friend has an AWD Cherokee. He only replaced two tires and he ended up replacing his transmission because of it.

[rickyd123]

I got some more info. She called the dealer. They said her Ford Edge is equipped with adaptive AWD, so it's safe to replace just one or two tires.

[RidingOnRailz]

Originally Posted by rickyd123

I got some more info. She called the dealer.
They said her Ford Edge is equipped with adaptive
AWD, so it's safe to replace just one or two tires.

Excellent.

You know I'm always harping on frequent tire pressure checks.

Definitely applies in the case of that AWD Edge.

[InvalidNick123]

technically they aren't lying, if the tread depth is too different it can actually mess up the awd system on those fords. but if she can find a used tire with similar wear it would save her from buying a whole new set.