The 420 series are just 40 series with a 20mm hex pattern.
40 series tires are wider than maxx sized tires, they are generally 3.5 inches wide where maxx sized tires are 2.75 inches wide (bowties) and just a hair shorter (5.4 versus 5.5)
Is the general concensus to use maxx sized wheels and tires for 1/8 truggies? What are the costs/benefits to using these over the 40 series rims and tires? Here are a few:
Benefits of maxx sized tires: narrower, more variety of tread patterns, lighter
Benefits of 40 series tires: wider, more traction, more stability?
Sorry for highjacking your thread, but this should help out with responses, i hope.