My 88 300 TE with 125K miles, good Pirelli tires, gives me excessive road noise at quite slow speeds when I travel any but glass smooth streets. Tire pressure is about 32 psi, seems to be coming from the rear. Shocks seem to be o.k. and bushings also are visually o.k.
Is this normal for this model - I've just bought the car and it is my first gas MBZ. My last 240D was quiet and my 300SD is very quiet.

You could try dropping your tire pressure if that's 32 cold. Seems a bit high. Pirelli's can be a bit noisy with high pressure. Also wagons tend to amplify noise more than sedans..

1988 300TE with 198k miles. Road noise was a problem until I switched to Michelin tires. Original Continentals were very noisy. I also just replaced the front shocks with significant improvement in handling and "bump" noise. However, not a cheap project at over $500.