I agree with nzcarnerd, one inch tire diameter difference at ~30 inches only changes overall gearing by about 3%. We just toured with several 20s and 30s Studes and Willys and for the most part 40-50 mph was not unusual on good flat roads, many of them lower end cars for their time than yours. I was especially impressed by the '23 Baby Overland and '26 Whippet, they kept right up. We were on the new car end in our '41 President.