spamgnome

Vehicle: 2013 GLK250
Miles: ~70,500

I'm up for inspection in the next 2 months, and the rears will definitely not pass inspection. I know in many AWD vehicles it's highly recommended to replace all 4 tires, and some shops basically mandate it. Does anyone know if my vehicel fall into this category?

Mmr1

Selling you 4 tires when you need one or two is a scam to rip off people . The MB manual says do not purchase different sized tires when replacing them . Just buy the size you have

habbyguy

It all depends on the type of AWD system your car has. With a RWD or FWD (only) car, you can mix and match front-to-rear (lots of staggered tire packages have very different diameters front-to-back).

It's tough to find a definitive answer from some manufacturers, but (for example) with my BMW xi (AWD) a difference of only 0.5% front to rear is tolerable. That means if your front tires are at half tread, putting new rear tires will exceed this. Will your car explode backing out of the driveway? Nope. Will it stress the (BMW) transfer case? Without a doubt. Enough to hurt it? Dunno... you make that call (I'm all for staying well within that limit so I don't have to sweat it). I've never seen a spec for the GLK X204.

Having had my transfer case apart on my X204 GLK, I have to think it's not as big a deal, as there are no clutches, but "just" a collection of helical gears that apparently portion out the proper amount of drive to the rear wheels. It appears that the front wheels are driven 100% all the time. I'm not sure what happens if you mount larger tires on the rear though - I'm not sure that planetary gear system can supply MORE "spin" to the rear propshaft than the (fixed) front propshaft gets. And of course, the best option is to have the same tread depth all around, but if you have to have two "better tires" put 'em on the rear (where hydroplaning or losing traction in a wet corner are more likely).

John CC

If your front tires are worth keeping, then I wouldn't hesitate to put new tires of the same size designation on the back. OTOH, if you're just one tire rotation period away from replacing the fronts, then I'd probably do all 4 now. If there's a big difference, look at your rotation schedule...

calder-cay

...
Re-read both of these statements ... I comPLETELY agree with both, based on my 40+ years of diverse vehicle ownership.

NYCGLK

a new pair should be fine as long as of the same same (preferably brand/type). I would not recommend replace one tire. I did that once and the car pulled, ended up putting it to the rear. And I believe dealer did this as I had tire coverage through the dealer for 5 years and they didn't try to upsell. This was probably 11 years ago with this car.