Army, they are the stock 185/75R14 tires IIRC.
Leathermang, I check mileage regularly and it's usually around 25mpg in cold weather and peaks at 28ish in hot weather. I haven't actually put the calculator to it and averaged my numbers but that's ballpark.
PawoSD, amen on the different mindset. This morning I actually PASSED two cars (one on a two-lane road) so it's looking promising.
With only about a day and a half on the alteration I think it's going to be alright around town but will need some attention on the highway until up to speed. Once up to speed the change is very pleasant. Picture a cabin noise level of 59 mph with a road speed of 70 mph.
I'll report more later. I'm going to fill up and zero the gps today. Should need filled up by Sunday at which point I'll have some results even if inconclusive. If I have time I'll adjust the valves Saturday.

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1983 M-B 240D-Gone too.
1976 M-B 300D-Departed.

"Good" is the worst enemy of "Great".