My 2008 4matic C300 Sport has the 225/45 R17 and the 245/40 R17 tires. I think that's the OEM size for this car. But. The sticker inside says different. What gives? Cold I run all 4 tires of the same size on a 4matic?

Have you checked your VIN to see if your car is actually a Sport? The tires listed on the door jamb sticker are most likely the tires the car came with from the factory. They could have been changed by a subsequent owner or even by the selling dealer at the buyer’s request. You can run either tire size on the rear, but if you have the 17x8 or 17x8.5 rear wheels, you probably should stick to the 245/40R17 tires on the rear.

Yes the best is to check VIN. I assume 2008 is the same as my 2011, Luxury version has four tires of the same size, Sports has staggered sizes. I kind of regratting buying the sports version that tires are not rotatable.

Mine has the wider rear rims and i have those same sized tires on. 225/45R17 Front, 245/40R17 rear.

Looks like that sticker is assuming you have the same sized rims on front and back.

Your Operators manual in the glove box should list all the appropriate tire sizes for yours depending which size rims you have.

Your VIN is visible in your pictures of the tire & load information label, so I looked it up.
You have a 204.081 which is definitely a Sport model.
The standard wheel/tire configuration is 225/45 R 17 on 17x7.5 rims front and 245/40 R 17 on 17x8.5 rims rear. You have the 245/40 rear tires, so you probably have the 17x8.5 rims.
But it was possible to order the car with the same rims and tires on all 4 wheels. Since you have the tire & load info label for the same tires all around, I suggest taking off one of the rear wheels and checking the size. It will be on the inside of one of the spokes as 17 J 7.5 or 17 J 8.5 and an ET that is the offset. If you happen to have the 17x7.5 rims, you are fine with going to the same size tires all around.

According to your vin the car came with all 4 same size wheels.

On mine which also happens to be a 204.081 it shows -R22 17" 5-SPOKE LIGHT ALLOY DESIGN WH.W.MIX.TIRES- Mine has the staggered wheels, and also confirms this on the door sticker.

I asked my "friend" ChatGPT whose answer is "The 2008 Mercedes C300 4MATIC Sport typically has non-staggered tires, meaning it uses the same tire size on both the front and rear wheels. However, Mercedes did offer optional packages and configurations, so it’s a good idea to double-check your vehicle's tire specifications, which you can find on the driver's side door jamb or in the owner's manual."

I guess they could have been swapped by a previous owner. They are the staggered 17's which is fine. I see these staggered sizes are well within the 1% for 4Matic AWD. I just wasn't sure if the cars gear ratios were set up for different sized tires front and rear (height). Thanks for the assistance. Definitely helped me out. Thanks all.

Which rims are on it, are they Mercedes rims or aftermarket?

If it were me I would be removing the wheels just to check to see what the rims say on the inside. See if they really are the staggered rims.

They are Mercedes wheels, and they are definitely staggered. I have them off. I will check in the inside for sizes just to satisfy myself. LOL. Thanks.