The handles broke off within 3 months of service in a Quick-service restaurant kitchen. While it is small enough to work in a compact kitchen, it was not durable enough to suit our needs: frequent loads of 100+ lbs over door saddles to get to our outdoor walk-in. Maybe in a less fast-paced kitchen it would hold up better, but in fast food, speed takes priority. The underside of the shelves is difficult to clean because the plastic reinforcement divides the underside into multiple small sections, each with tiny corners to get food particles stuck in if something splashes up.
Below is a link to a commercial bus cart caster that should work with the update cart... https://www.etundra.com/restaurant-parts/janitorial-parts/cart-dolly/commercial-bus-cart-caster-with-4-in-wheel/
The distance between the shelves are 11-5/8".
The height between the shelves of the Update International (BC-2416LGZ) - 31" Aluminum 3-Tier Heavy Duty Bus Cart is 11-5/8".
The bottom shelf is available for the Update International - BC-2416LGZ. To order that please call sales at 888-388-6372.
The casters have a 4" diameter.