DrRx

A quick question directed primarily at any of our European members!

I am using 235/60-R17 winter tires on my GLK250 BlueTEC diesel. Can anyone tell me what the MB recommended inflation pressure is for this 17" tire (ie. from the sticker on the gas filler door or on the B-pillar)??

Here in North America the GLKs only come equipped with 19" or 20" tires and the sticker only applies to these sizes, and MB USA, MB CANADA, and all the dealers I have called are just quessing. However I know that the 235/60-R17 is the standard specification in Europe, so I was hoping someone could send me the information posted on their car - a photo would be great if possible!

I have checked everywhere on the web, and I am finding conflicting info. For partial load, some say 2,3 bar (33 psi) F&R is recommended while others say 2,6 bar (37 psi) F&R, so I am not sure what to believe.

Many thanks in advance!!

koalatm

I'd go somewhere in around 38 psi for winter tires. This is what I've always typically run.

Quite frankly anything up to about 44 psi is pretty safe. When I used to auto-x we'd always overfill the tires and then slowly let out air to "tune" the handling as you got used to the level of grip.

jrct9454

I'm running that size with Michelin MXV4s year-round, using aftermarket Rial wheels [made in Germany, no less] - I generally set them at 36-38 psi all around.

Our 19's are permanently stored until I sell the car. One of the results of the switch is a ride that's more E-class than GLK.

And incidentally, the 17s are standard EVERYWHERE else in the world except North America.

JohnMichael

Who do think comes up with the factory recommended pressure? The engineers of the car - they design a certain amount of rubber on the road - low pressure more rubber - more pressure less rubber. Also they design the pressure based on how much flex they want in the sidewalls as this also effects keeping that rubber footprint size on the road for cornering. ABS brakes, ESP, 4 matic, all are inputs that determine the size of the tire footprint You crank up all your tires to 44 and you lose rubber on the road, increase stopping distance in emergencies and lose traction. The difference between front and back pressure when it is recommended is also important for handling as the weight distibution (how much weight on the front two tires compared to how much on the rear have) changes depending on acceration and braking. I am constantly amazed at how many people pick some arbitrary number out of their head for tire pressure. It is extremely important to have the recommended pressure if you want to have the car operate in all conditions as the engineers designed it. The biggest mistake people make is to just read the tire maximum PSI on the tire and put in that amount - big mistake always go by the manufacturer recommendations.

DrRx

EXACTLY! Hallelujah! That is precisely why I am trying to ascertain the engineer-recommended inflation pressure for the 235/60-17 size tires that are standard edition on the GLK everywhere outside North America. I am amazed that neither MB USA or MB Canada have access to this information, despite dealers selling winter tire packages in that size.

Therefore I remain hopeful that someone in Europe, Asia or South America can provide that information from their fuel filler door sticker!!

Mort

Here is a tire pressure recommendation from a google search. Scroll down the page to GLK (204) 17" Wheels 33 psi front and rear.

http://www.puretyre.co.uk/mercedes-benz-tyre-pressures/

This is the same as our 2011. Cold pressure 33 front 33 rear normal load. Cold pressure 35 front 39 rear maximum load. Our car came with 20" wheels.

koalatm

I can assure you it's not at all arbitrary to pick a number like 38 psi. I find on most vehicles this slightly higher inflation increases fuel economy quite noticeably, and allows for a more responsive turn-in.

44 psi was an example I used for a more specific application (auto cross). This was merely to illustrate that it is "safe" to use, not necessarily optimal. After each run you'd usually let out a bit of air anyway to get it to where you wanted the grip and response to be, which in the case of the car I mainly used to auto-x was around 42 psi (hot).

I would typically only run lower pressures if I were drag racing, as the tires will find traction easier with less inflation.

That being said if someone questions recommendations then look no further than the typical door jamb of any typical vehicle - they're almost always in the 31-33 range.