I finally needed to use my spare tire, at 167,000 miles on a 1999 ML430.

1. Could not get the quarter turn handle that holds the center of the spare in place to turn, no matter how much "persuasion" applied

2. Slid under the car (after getting tire replaced and the car into my garage) to see what the issue could be. The spring loaded mechanism which holds the tire in place was obviously severely rusted since it is fully exposed to the "elements" under the car.

3. Used PB Blaster on the mechanism, scrapped off the rust and ultimately got the tire out
4. Tire pressure 22 lbs .... should be inflated to 60 lbs.
5. Wheel heavily caked with LOTS of dirt, NOT even distributed.

At 22 lbs, the spare probably would be been pretty useless, fairly quickly. Just thought I'd share my experience.

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Jim

I take the spare out every time I rotate the tires. I use the spare as the temporary bolt on when I rotate the regular tires. This gives me a chance to check on the condition of the spare, make sure it is holding air and have enough pressure. It also gives me a chance to work that mechanism and lubricate it. I have discovered that the valve stem had a leak and rendered the spare useless. So I promptly got it repaired. It was discovered when I did the tire rotation. This really saved me the hassle when I did need it in some odd occassions. Just my thought.

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98 ML320 (gone but not forgotten)