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[QUOTE=calder-cay;8620227]Well I grabbed my 2014 GLK manual (I think OP has 2013) out of glovebox, which includes coverage of 4Matic (we don't have a 4Matic).
There's no mention about having to replace all four tires, because one is bad, and no mention about flats, except how to install the spare.
However, there is this bullet point in the Important Guidelines sub-section under Tires and Wheels section:
When replacing individual tires, you should mount new tires on the front wheels first (on vehicles with same-sized wheels all around).
Is the glk a fwd car that shifts to awd on demand? That is a different story. No manufacturer recommends a single tire replacement on a full time awd car. They would at least request both on the axle so the diff knows where it is and does not work too hard. This just happened to a friend with vw r awd. Had to wait for tire rack to shave the new tire to spec before anyone would install. Luckily had extra set of rims cause the tire shortage made it difficult.
The only reason to mix tires is if you're cheap, can’t afford it, don’t care, or are not a car person. This information is not new. There was no scam. Same thing happens when a nail goes in the shoulder of a tire with more than 5k wear in it, all four tires or risk your diffs. Been though it with awd trucks, sports cars, etc. I also replace tires before they wear out because , safety.
or, we can believe Mr Costco (a cheap **** waste store for cheap as **** or fat eaters that also ruins the economy, imo ymmv) has undercover tire techs that he converses with for every transaction and also mr Costco infiltrated every other high end tire shop that keeps people safe. Be really careful out there as the liars are out for tiars This is really similar to when I went to Home Depot and the guy told me I should use nails when the plans called for screws and the whole project fell apart. Apparently the nail industry infiltrated Home Depot so they could attack the screw industry from the retail sales floor. Some really sneaky spies out there.
Last edited by Baltistyle; 08-21-2022 at 06:12 PM.
... what does the MB GLK 4Matic Owner's Manual state? Any guidance?
Nothing about tire diameter or wear when replacing fewer than 4 tires in the 2015 manual. It only says use the same brand, construction, tread pattern.
Subaru AWD system is very different from 4Matic. It’s more like 4WD.
Costco response could be any of ignorance, incompetence, laziness, or dishonesty. Hard to tell, but the result is the same.
I do replace both tires on the same axle if the difference between new and the other tire is >5mm for braking performance. I have never worried about front/rear differences.
When replacing tires, you should mount new tires on the front wheels first (on vehicles with same-sized wheels all around).
Interesting. That runs counter to everything I've been taught, and learned the hard way. Better tires on the front is a good way to get the rear wheels to come around in front of the front wheels...
2014 GLK350 base model (active) ; 2001 E320 base (retired); 2001 Wrangler soft-top
Originally Posted by John CC
Interesting. That runs counter to everything I've been taught, and learned the hard way. Better tires on the front is a good way to get the rear wheels to come around in front of the front wheels...
I can't seem to find that line in my 2014 manual.
See my subsequent post in another new thread, and possibly reread my corrected post above
2010, 2013, 2014, it doesn't matter. The better tires should be on the back (IMHO).
Loss of traction in the rear (braking, or acceleration in rear wheel drive cars) encourages oversteer.
TMSAISTI!
If I were installing TWO new tires on the same end of the vehicle I would put them on the front. The front tires, I imagine, wear down sooner as the fronts typically carry a greater weight, do the steering, do the majority of the braking and some of the acceleration (4Matic). Once the diameters of the fronts and rears were about equal then I would go to a tire rotation scheme - fronts to back and backs to front for "x" number of miles/km. and then repeat process.
Pre-ABS and pre-traction control days a vehicle swinging around would, no doubt, be a bigger concern and warrant the newer tires going on the rear.
Sorry, but I won't be relying on ABS and traction control to keep me safe...
Nor would I. Having said that, I wouldn't rely on having newer tires in the rear keeping me safe. A million and one things at play when it comes to driving/automotive safety.
If I were installing TWO new tires on the same end of the vehicle I would put them on the front. The front tires, I imagine, wear down sooner as the fronts typically carry a greater weight, do the steering, do the majority of the braking and some of the acceleration. Once the diameters of the fronts and rears were about equal then I would go to a tire rotation scheme - fronts to back and backs to front for "x" number of miles/km. and then repeat process.
Pre-ABS and pre-traction control days a vehicle swinging around would, no doubt, be a bigger concern and warrant the newer tires going on the rear.
This what I was taught. Fronts always get the better tires, primarily because of steering control. The rear is controlled by throttle. This became underscored with the popularization of fwd cars where throttle and steering are up front which most car platforms even with awd (fwd plus rear to some degree) rely on.
Last edited by Baltistyle; 08-22-2022 at 12:09 PM.
2014 GLK350 base model (active) ; 2001 E320 base (retired); 2001 Wrangler soft-top
Originally Posted by Baltistyle
This what I was taught. Fronts always get the better tires, primarily because of steering control. The rear is controlled by throttle. This became underscored with the popularization of fwd cars which most car platforms even with awd (fwd plus rear to some degree) rely on.
Agreed.
Back in the 70's or so, it was recommended to put new tires on the rear, but that makes no sense, as @Baltistyle states above.
Back in the 70's or so, it was recommended to put new tires on the rear, but that makes no sense,
Sure it does. Even a FWD car will spin out if you loose traction on the rear wheels. Cars are much easier to control, and it is much easier to recover from a loss of control if they under steer.
I'm not relying on good rear tires to keep me safe, I'm relying on good driving skills and consistent, predictable handling. It's worked for me for almost 60 years and I see no reason to change things up at this point.
My 4Matic was a 2005 ML350 and it definitely had this statement. Discount Tire made me sign a waiver to put the 2 new ones on the front.
On my RWD cars I usually buy 4 at a time. But if I have to replace 2 because of damage, I put the new tires on the rear.
that’s enlightening since all the salesman tell me the opposite, but then I think they are lying for commission and from stupidity. Or being a con artist . Being a con artist is the worst crime. ****ers should be hung or tar and feathered . Which is worse than being shot . It’s a bad death .
A few things should be kept in mind... the first post by the Original Poster is in reference to the 4Matic so that's what we're discussing (or at least should be).
In regard to the links provided...
Discount Tire - unable to read it as it's blocked in my country of residence.
Firestone -
"FOUR-WHEEL DRIVE AND ALL-WHEEL DRIVE VEHICLES
Things are a bit trickier with four- and all-wheel drive vehicles. Even tiny differences in tire diameters on an axle, or between tires on different axles can lead to a glitch in the drivetrain system. Usually, all four tires are recommended to be replaced at once, but always check your vehicle manufacturer's recommendations for specific guidance regarding your vehicle."
Discount Tire -
"Replacing AWD Tires
If you are looking to replace all-wheel drive tires, we recommend replacing all four at once. While it may be tempting to replace only two at a time, mixing new and worn tires can create a size difference from front to back, which can lead to damage to your vehicle."
Further, in the two of the three links I can view, there is nowhere that they state it's their "policy."
With no other considerations needed, I would always put new tire(s) on the rear of a vehicle. But, with the 4Matic, I also want to consider possible damage to the 4Matic system so I would put them on the front since they should wear down more quickly getting them to the same diameter as the rears - then rotate them front to back. Apparently, you could also get the new tires shaved down to the same diameter if someone wants to go that route.
Whether or not it's important to have the tire diameters matching, or at least being very close, is another topic/debate. Some are convinced of its criticality, others not so much.
Nowhere in the MB manual does it agree with that , I view this as a SALES PITCH as just that , a scam to sell 4 tires.
You don’t damage the 4wd system or differentials by driving off road , on sand or curved roads , the 4 matic differentials are NOT LOCKED!!
it’s all a SCAM, by tire companies to sell tires.
Installing different sized tires is not advised. But the MB manual makes no statement about differential damage, only suspension!
I say it’s a scam. Your differentials are not locked or locking on 4 matic!
so I’m confused when I read this. What does it mean when it says ALWAYS replace the axle with matching sizes. Does that mean one worn tire and one new tire? Perhaps I need to understand what same means. Can someone help? I think the Mercedes’ technical writer is in cahoots with Mr Costco.
2014 GLK350 base model (active) ; 2001 E320 base (retired); 2001 Wrangler soft-top
Originally Posted by Baltistyle
so I’m confused when I read this. What does it mean when it says ALWAYS replace the axle with matching sizes. Does that mean one worn tire and one new tire? Perhaps I need to understand what same means. Can someone help? I think the Mercedes’ technical writer is in cahoots with Mr Costco.
For example:
If you're going to replace the LF tire, it needs to be the same size as the RF.
If you're going to replace the RR tire, it needs to be the same size as the LR.
This is for those vehicles that have different size tires on the front compared to the rear.
For example:
If you're going to replace the LF tire, it needs to be the same size as the RF.
If you're going to replace the RR tire, it needs to be the same size as the LR.
This is for those vehicles that have different size tires on the front compared to the rear.
Sorry, that was sarcasm to show a worn tire with 20k and new tire are not acceptable on same axle as per Mercedes. A tire with 20k is something I never see cause I believe in preventive care. The photo covers many of the other thoughts on the thread, directly from the manual as Op asked for. It pertains to stagger in the cars that have that OR wear. Though, an exaggerated example is how bad driving for a long time on a spare can be for the diffs or what can happen if awd is towed improperly. The diffs can take it until they can’t. If a person replaces one now and one next time, follows that pattern and the tires are always out of sync, the diffs are running counter to design, perhaps in tolerance but likely at and end of the range.
Sorry, that was sarcasm to show a worn tire with 20k and new tire are not acceptable on same axle as per Mercedes.
I don't think that is what they're saying at all. I think they're saying if you have e.g. a 205-50/19 on one side of the axle, don't put a 215-50/19 on the other side.
The only mention I've seen anywhere about wear levels is to pair the best of the old tires on the rear axle with the new tire.
So height is no longer a measurement? It says size, not width. So also consider 205 45 19 vs 205 50 19 is 26.26 vs 27.07 inches respectively. When a tire wears over twenty k miles it no longer has the same height and could be equated to the example. Theres tremendous amount of info about differentials and the tolerances. Having driven awd for the past 25 years, I've tried all the different tire "things" due to different economic circumstances. After I replaced a diff, I no longer gambled with tires.
08-21-2022 | 06:04 PM
This is really similar to when I went to Home Depot and the guy told me I should use nails when the plans called for screws and the whole project fell apart. Apparently the nail industry infiltrated Home Depot so they could attack the screw industry from the retail sales floor. Some really sneaky spies out there.
