Correct Tire Pressure
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Newbie
Joined: Aug 2018
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Mercedes AMG GLC43 4matic
Correct Tire Pressure
Hi guys recently I got a 2018 Mercedes AMG GLC43 4matic with 21" Rims, I took possession of the car with all four tires inflated to 330-340kPa(47-49psi), at the fuel cap it recommends 220/220kPa(31psi)[Front/Back] for partial load, and 240/260kPa(34/37psi)[Front/Back] for full load. Now i'm wondering isnt 220kPa a little low(if based on fuel cap sticker recommendation) and 330kPa a little high(based on what was inflated at the dealership), I checked with the dealer and they told me they are inflated to a higher pressure as the rims are huge and there are cases where people rupturing their tires(when driven over huge potholes) because of the low profile of the tire when inflated to partial load. I would like to ask the other owners with the 21" rims with what is recommended on your fuel cap sticker?
Senior Member
Joined: Apr 2017
Posts: 259
Likes: 44
From: Denver, Colorado
2018 GLC300 4matic SUV
Shipping pressures are very high, typically 45-60 PSI depending on the tires. The dealer is supposed to reset them to the correct level prior to delivery, as the car is not supposed to be driven around with the tires so overly inflated. The ride would be horrible, too. If your car was delivered this way, then your dealer probably just forgot to perform this work.
The fuel cap sticker is the most complete info. Most drivers should use partial load guidelines unless carrying a heavy load. I've heard many times that people receive their cars as I did: With the tires set to the full load pressures instead of the partial load pressures. I think this happens because the dealer employees look at the door sticker, which shows the max load pressures, instead of the fuel filler sticker with the complete list. The ride on mine was awful until I figured this out.
My personal opinion is that your dealer's comment about tires rupturing after encountering potholes when inflated to the recommended partial load pressure is BS.
The fuel cap sticker is the most complete info. Most drivers should use partial load guidelines unless carrying a heavy load. I've heard many times that people receive their cars as I did: With the tires set to the full load pressures instead of the partial load pressures. I think this happens because the dealer employees look at the door sticker, which shows the max load pressures, instead of the fuel filler sticker with the complete list. The ride on mine was awful until I figured this out.
My personal opinion is that your dealer's comment about tires rupturing after encountering potholes when inflated to the recommended partial load pressure is BS.
Thread Starter
Newbie
Joined: Aug 2018
Posts: 2
Likes: 0
Mercedes AMG GLC43 4matic
Shipping pressures are very high, typically 45-60 PSI depending on the tires. The dealer is supposed to reset them to the correct level prior to delivery, as the car is not supposed to be driven around with the tires so overly inflated. The ride would be horrible, too. If your car was delivered this way, then your dealer probably just forgot to perform this work.
The fuel cap sticker is the most complete info. Most drivers should use partial load guidelines unless carrying a heavy load. I've heard many times that people receive their cars as I did: With the tires set to the full load pressures instead of the partial load pressures. I think this happens because the dealer employees look at the door sticker, which shows the max load pressures, instead of the fuel filler sticker with the complete list. The ride on mine was awful until I figured this out.
My personal opinion is that your dealer's comment about tires rupturing after encountering potholes when inflated to the recommended partial load pressure is BS.
The fuel cap sticker is the most complete info. Most drivers should use partial load guidelines unless carrying a heavy load. I've heard many times that people receive their cars as I did: With the tires set to the full load pressures instead of the partial load pressures. I think this happens because the dealer employees look at the door sticker, which shows the max load pressures, instead of the fuel filler sticker with the complete list. The ride on mine was awful until I figured this out.
My personal opinion is that your dealer's comment about tires rupturing after encountering potholes when inflated to the recommended partial load pressure is BS.
Super Member
Joined: Feb 2017
Posts: 703
Likes: 136
From: Northeast, USA
GLC43, GTI, X3, Mazda3
Agree with mtberman, use the fuel cap sticker. That said, I use 34psi all around for the 21's on my GLC43. Rarely have passengers or heavy cargo, so the 34psi seems to work well balancing sport/comfort for the stock Conti's.
MBWorld Fanatic!
Joined: Nov 2012
Posts: 6,130
Likes: 1,117
A gaggle of MB's
Man... I'm sorry it is becoming so/so common for a lot of Mercedes dealers NOT to take the time to check-in/reset shipping tire pressures...
Spot on Fuel-Filler-Door is reliable guidance - with a decent tire gauge - feel free to "experiment" with tire pressure variations +/- 2lbs - starting from 34lbs - drive each reset a few days to get impression of the change on handling/feel.
On larger-diameter-wheels/lower-profile-sidewalls - it is definitely trending up in sidewall flats for lower profiles in my area due to continued home-building-expansion - the size of the sh*t my techs take out of tires nowadays is mind boggling - and "pinch-flats" have gone up - not-so-much in my area due to potholes/road-hazard - we have awesome roads - but "pinch-flats" caused by curbing on parking-lot/city-turns...
Spot on Fuel-Filler-Door is reliable guidance - with a decent tire gauge - feel free to "experiment" with tire pressure variations +/- 2lbs - starting from 34lbs - drive each reset a few days to get impression of the change on handling/feel.
On larger-diameter-wheels/lower-profile-sidewalls - it is definitely trending up in sidewall flats for lower profiles in my area due to continued home-building-expansion - the size of the sh*t my techs take out of tires nowadays is mind boggling - and "pinch-flats" have gone up - not-so-much in my area due to potholes/road-hazard - we have awesome roads - but "pinch-flats" caused by curbing on parking-lot/city-turns...
Senior Member
Joined: Apr 2017
Posts: 259
Likes: 44
From: Denver, Colorado
2018 GLC300 4matic SUV
Above is the one on the door frame. I have 19s. Made in Finland!
Fuel door sticker. It shows the various wheel sizes available for the GLC along with regular load and maximum loads pressures for each. AMG will vary.
Junior Member
Joined: Nov 2017
Posts: 64
Likes: 6
From: Central Coast, NSW, Australia
MB GLC250
GLC250 here, in Australia.
Not the 43 with 21" rims, but 20" rims.
Dealer supplied at 41psi (280Kpa), I dropped back to the 32psi (220) as per placard.
After 11,000 Kilometers (6,835 miles) , I checked tyre wear and appeared to be higher on both outer edges.
Since then have run 36psi (250kpa), tyre wear more even now across the tread. (now 22,000 Kms or 13,670 miles)
Suspect you might find 37psi to 38psi to be your sweet spot on the 21" rims.
My subjective thoughts:
1. Vehicle handles better with higher tyre pressure
2. Vehicle rides harsher with higher pressure.
3. Full lock tyre skipping/crabbing is less with higher pressure.
4. Placard pressures are too low....built for comfort
YMMV.
Not the 43 with 21" rims, but 20" rims.
Dealer supplied at 41psi (280Kpa), I dropped back to the 32psi (220) as per placard.
After 11,000 Kilometers (6,835 miles) , I checked tyre wear and appeared to be higher on both outer edges.
Since then have run 36psi (250kpa), tyre wear more even now across the tread. (now 22,000 Kms or 13,670 miles)
Suspect you might find 37psi to 38psi to be your sweet spot on the 21" rims.
My subjective thoughts:
1. Vehicle handles better with higher tyre pressure
2. Vehicle rides harsher with higher pressure.
3. Full lock tyre skipping/crabbing is less with higher pressure.
4. Placard pressures are too low....built for comfort
YMMV.
Last edited by Citizen613; Aug 24, 2018 at 04:48 AM.
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Senior Member
Joined: Apr 2017
Posts: 259
Likes: 44
From: Denver, Colorado
2018 GLC300 4matic SUV
Those are not normal duty recommended pressures. As described above, the door jamb placard shows only the "Maximum Load" pressures, which is what you should use only if driving with a full load of passengers and cargo. The ride quality will be poor if you use those pressures in day-to-day driving, especially in hot weather. The recommended pressures for your vehicle are 32 all around. From what I've seen on this forum, most drivers run 32 or slightly higher.
