The previous owner of my 300e 4matic had put 205/65/15 tires on the car. I understand that 205/60/15 or 195/65/15 is the appropriate size. Besides the speedo reading slightly slower than true speed, and potentially some better fuel economy, am I incurring any other side effects?

Thanks in Advance

Russla

If all four tires/corners are the same rolling radius then there is less of a chance of electronic problems. When you need to replace a tire or tires, replace the set. Differences in wheel speed between wheels trips the ABS/ASR. As long as the ABS/ASR sees all four wheels turning at the same rate you should be out of the red. BTW your odo will also be turning slower as well. The marginally taller sidewalls will be a bit more squishy than the proper height ones. Under extreme load you might get a hint of rubbing but I doubt it. The taller overall diameter of the tires will give you taller effective gearing so your acceleration will be muted somewhat. That is about it. Depends if it is annoying enough to warrant premature replacement. Oh, what size tire do you have as a spare?

Hope this helps...Lee