Can mismatched tires be used on AWD car?

[Ingvar]

So this is what happened. We just bought a fancy car for my wife. 37 000 miles still under warranty. Problem is, yahoo that owned it never did tire rotation and front end tires technically are done for. Rear axle ones are still good 30% tread left.
Now because they are 235/55R19, they are rather very expensive.
It’s a Japanese all wheel drive SUV. Naturally, my first thought is to get a pair of used ones to put onto the front end, drive on them for a year or so, then replace entire set.
Thing that bugs me is this. I KNOW you can not do this on a 4WD car with mechanical transfer case as when it’s engaged, it locks t-case. I had this on my Silverado. But, to my knowledge, AWD car does NOT have a mechanical t-case, more like a what they call viscous differential between the front and rear. Like a small size automatic transmission. I think, you can get away with having mismatched tires on front and rear in this case as there is no direct mechanical lock between front and rear when AWD engages.
Before I step out and buy a pair of used ones, question to esteemed colleges here.
Can or can I not? It’s rather expensive car to f-up this way.

Topic

[Ingvar]

Well, here’s Tire Rack article:

Replacing Pairs of Tires or Individual Tires

There are several suggestions that have been offered to drivers who are replacing pairs or individual tires on their four-wheel drive and all-wheel drive vehicles. Some vehicle manufacturers recommend that all tires maintain the same rolling radius and circumference, while others suggest that all tire circumferences remain within 1/4- to 1/2-inch of each other. Other vehicle manufacturers recommend that all four tires remain within 2/32-, 3/32- or 4/32-inch of each other, or within 30% of each other in relative remaining tread depth.

Regardless of the vehicle manufacturer’s recommendations, the least stressful application is when all four tires are the same tire brand, tread design and equivalent tread depth.

Before buying pairs or individual tires for all-wheel drive and four-wheel drive vehicles, drivers should read their vehicle’s owners manual or contact the dealer’s service department for confirmation of their specific vehicle’s requirements.

[wafrederick]

four wheel drive and all wheel drive vehicles,same tire sizes used is the only way to go.Have found four wheel drive systems in trucks not working all because of different tire sizes used and do damage to transfer cases.With all wheel drive,you don’t just replace one tire at a time.

[Douglas Haynes]

You can mix the brands but not the sizes and confirm that they are pretty close in actual size.

[PaulKim]

Go for a set of new (or used) 18″ wheels and tires to save yourself a lot of money in the future. 19″ is a scam and money pit. Heck, if you got 20s it would also be cheaper than 19s lol

[Mike]

There first thing I’d do is rotate the tires and put the better rear tires on the front.

I wouldn’t be farting around with mismatched tire sizes. You could be setting yourself up for unsafe handling and weird ABS issues.

Having said that, it might be possible to find a different tire size that specs out pretty close to the rolling circumference of your 235/55 tires. The sidewall height of your stock tires is 129.25 mm (55% of 235 mm). You’ll have to do the math on any prospective tires you might find to see if the sidewall height comes close to 129 mm. The thing is, if you mess around with tire width too much in order to get right sidewall height, you’ll be running into fender and suspension clearance issues.

[Author]

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