300E 5 speed. Talk to Good ol Larry Bible our resident owner of a 300E 5 speed who knows that car very well.
How is the cars maintenance been done over the years, what is its mileage etc etc. you say excellent condition. It could be a number of things. I would start by using the search feature of the site, to search for things like SRS light 300E, or search for 300e srs and such. you should geta great amount of posts that might already have the answer. But you can still geta good answer here.
When you get it home, make sure you have your mercedes tech give it a good fluid changing of fluids that are needed, coolant should be ensured to be Mercedes coolant. spark plugs gapped right, air filter replaced if necesary, tune up stuff basically to make sure your baby is running right. Then have or check out the electrical items, OVP, SRS relays or sensors, etc etc.
Check the wheels and tires forum, you can up the tire size to a more aggressive size, but I believe the 205/60 is the sportline tire size.
Go to www.tirerack.com
and check on the tires and reviews. Also call luke at the tire rack. He can help you get the right tires for yoru needs, and can get them to you and find a place to put them on for you wherever you might be in this country.
Correct me if I am wrong here as well please...