Starting with a solid billet of 6061-T6 Aircraft Aluminum we CNC machine super strong wheels with 5mm more offset for your Maxx. Combined with Proline BowTies or StepPins makes these a lethal combination.
Features:

Polished to a high luster
Super Strong and can take even the worst abuse. We've designed the wheel to withstand a simulated 500lb lateral impact force. Extensive abuse in the real world has yet to produce a failure.
When combined with a tire like Pro-Line's BowTie the racing wheels are 50 grams lighter than the stock Traxxas tires and wheels.
NEW: The recent arrival of Tamiya's new monster truck the Terra Crusher prompted me to strap on a set of our Racing wheels. They fit perfect. The offset chosen for this wheel matches perfectly with the Terra Crusher. The real bonus is the weight savings. Switching a SMRW & Pro-Line Bow Tie against the stock Tamiya wheel & tire will lighten your Terra Crusher by 2.25lbs!

Here are the specs. How much lighter are the spi ones? Are they stronger?