Anyone thinking of changing wheel size from a 14" on their diesels DO IT.
 

About a month ago I cruised down to Tuscon on my 83 sd and I couldn't get it above 65 comfortably. It had the standard 14's on.

I put 15's on from a 87 420 sel, I was driving 80 today around Phoenix not even thinking about it. Freakin Awsome. Ofcourse I have been doing other things to the car to help the cause. This next weekend I am replacing the upper control arms for heck of it.

I doubt it was the wheels. Have you repaired the fuel supply system or changed the fuel filters?

What size tires did you install on those wheels?

I kept the originals from the 420 sel. 215 65 15.

Im talking about the feel of the car, I was afraid to take it above 65 before. I have replaced the fuel filters, other maintain 4 months ago.

Did you change the size of your tires as well? If not you are probably getting false readings from the speedo. In order to run a larger wheel and get accurate readings you need to adjust the tire size so that the radius matches that of the 14" wheel and tire.

Changing wheel size will not increase speed. Probably actually slow you down, effectively, as whatever 15 inch wheels you bolted on to the car will likely weigh more than 14 inch bundts. Your speedo is probably off.

Just having good tires is all you need.

I would also suggest riding 'IN' your SD as it is much safer this way.

I would argue that there is no way that swapping from 14s to 15s will make it easier to get over 65. Just doesnt make sense.

Interesting you bring that up, the speed cameras around town showed my speedo five over with the 14's. The 15's show me only two miles over. The odometer was correct the 14's. I pass alot of people now where before I was following.

I like how everyone missed that he felt comftorable going faster, not that his car was actually faster. :rolleyes:

By installing larger tires you increased your final gear ratio, you are going faster for the same engine speed. If you had trouble going 65 mph with the old wheels/tires, they had some kind of problem.

Yup, like others have said, new tires will make a HUGE difference in the comfort and stability of a vehicle, any vehicle on the road.
if yours were hard/worn/damaged/bulged... etc, new smooth tires would make a huge improvement. don't matter if they are 12" or 24"... smooth balanced MUCH better than old warped!

That is somewhat subjective. The OP could also be referring to the car's level of comfort getting up to speed. Bottom line, I believe the 14 inch tires were probably just crap.

see ^

The feel of the car, Don't really understand why Mercedes would even use a 14 on that size of car. This car is starting to feel like the Volvo 740 I used to have.

I really didn't want to start a flame. Just comment invade someone down the road wanted to change sizes.

I like my 15's, but it could be just subjective.