That axle swap is a 23% rise in axle ratio, what you might try is a 205/75/14 tire that will give you about 15% rise in axle ratio and might be cheaper & easier to do, not to mention easier to swap back. The standard axle ratio of 3.69 in the 240D would then become almost 3.00. Remember this car and gear ratio was factory with tires from 185/70/14 to 205/70/14, which is on average a 2 inch difference. These larger tire will easly fit as it was designed to except a 15 inch tire in 3rd world use, let me know if you want info about those tire sizes.
I have the 205/70's and I can hit about 80 mph on the flat and with long enough run maybe 85 mph. With 185/70's I could push 85 mph. I average 31/32 highway at 65 mph (gps) and love the car. Mater of fact I have decided not to move up to a turbo 300.
