I am driving from Salt Lake City, Utah to Old Lyme, Ct. in my new 1988 300E, which is in unbelievable condition. I need to replace the tires as soon as I get back, as they are pretty worn and have been run by the previous owner in an unbalanced condition. They kind of drone like off road vehicle tires, and vibrate a lot on anything but the smoothest pavement at any speed. On smooth pavement the wheels will start to shake a bit over 65mph. Anyway, the question is the correct tire size. The manual says it takes 195/65 VR-15's and the car has 205/60 VR-15's, which it would seem are mathematically about equal to the manual requirement in diameter, so the speedometer seems relatively accurate. I was wondering if 215/55 VR-15s might be ok, or if I should stick with the factory recommended size.

After driving for approximately 6 hrs straight at speeds in and around 80 mph in Utah and Colorado, the SRS light started coming on on the dash. It would stay on for 1-3 seconds, then go off for 15 to 20 minutes. This slowly and erratically changed to intermittently staying on for up to 20 seconds, and then blinking repeatedly, to staying on for two hours. When I shut the car off and start it up either the next morning or after a nature break, which is a relatively short time, it stays off for a few hours and then the pattern starts again. Any ideas on what the issue might be and how to fix it?

Thanks, Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)