This site will help with gear ratios and speeds:
http://www.onlineconversion.com/bigger_tires.htm

What is your tire overall diameter?

My guess is that you could not pull the 2.41 rear and an OD with the 235 unless a strong tail wind with a good down hill.

2.41 could be about right if you had the SM420 4 speed, then you have a low gear to start with, and the 2.41 is effectively an overdrive once you get to 4th.

Grigg


•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-