prad

The right front tire on my 2014 GL 350 got damaged. All the four tires have about 17k miles on them. Discount tire says I must replace them all together or I’ll screw up my all-wheel drive system! The MB dealership looked at it and says that it’s just fine to replace the damaged one alone. According to the dealership, these tires have Seven thirty seconds tread depth, so I can go ahead and replace just the one tire and keep the rest. I would like to get your thoughts on whether to replace all ($1100), or just one of them (~$250)? These are Pirelli Scorpion 275/50/20.

aeggroup

I would change 2 front tires and just store the old good tire in my garage just in case.

JMCarter

You might very well get matching tire(s) that won't balance out well, look at the thread on your current tire. Save yourself some grief and go with the new Michelin, I'm very happy with my new set.

captivabenz

I would go with just replace the one tire, and rotate all tires every 5000 miles.
I have the exact same tires, with almost 25,000 miles, with no vibration or noise problems at all. The tread is still deep, I would estimate another 7500-10,000 miles left.

fabbrisd1

I agrre with AEG... I'd replace the pair - run the fresh on the front..

prad

Thanks folks. I was told by my dealership that I could replace just the one tire that's damaged. Another dealership said that I should replace all the four or I could damage my differential and transfer case. Yet another dealership said that I could just go with two.

So I called Mercedes customer care and a product specialist said if the remaining tires are at least 3/32 (below which point they are pretty much worn out anyways), I could just replace the one tire. But based on what I gathered, I'm worried that if I replace two, I could still damage the transfer case in the long run.

So I'm trying to get a response from MB in an email, so I'm covered and not voiding their warranty if anything goes wrong in the future. Mine is a 2014, so still have another 4 years of warranty left.

Btw, this blog kind of agrees with what the MB product guy said: http://www.4x4abc.com/4WD101/diffautoAWD_AWD.html

prad

Update: A product specialist from MB USA HQ called me and confirmed that I could just replace the one damaged tire. He said that damage could occur to transfer case or differential in AWD systems with viscous couplings, but the GL does not have viscous couplings. He followed up with an email as well.

91stealthes

I would assume the tire came with 10-12/32nds of tread when new, so you will be anywhere from 3-5/32nds difference.

If Mercedes told you it was fine and you have proof for if your diff burns up, great. Though, I personally would not run a new tire alongside 3 tires with 17k miles on them.

My last 4 vehicles have all been AWD and it seems the industry standard is to keep all 4 tires as close as possible. I found an article from TireRack for you and I pulled an excerpt below and provided the link for your reference.

From TireRack (http://www.tirerack.com/tires/tirete...sp?techid=18):

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.