Only the 33/10.5s are huge not the 29.5's. I run the true 10.5 stiff sidewall on a 12" rim with 11lbs of air and only seem to get 25-30 passes also. (1.25 60') I wish they made a 31" true 10.5!

The 2 tires appear to be dam near the same size

3062S 29.5/10.5-15S 27 M5 9555 10 13.2 10.2 29.9 94

3062W 29.5/10.5-15W 30 M5 9555 10 13.6 11.2 29.6 93