What is the robot’s operating environment (indoors, outdoors, summer, winter, rain etc.) indoor possible water dripping environment, so IPX4 would be nice to have.
Regarding payload, is that on a flat surface or up an incline? flat surface
Do you have an idea of your budget? up to 7K per unit for R&D. production 3-5K in small volume (10-20 MOQ)
Do you have any other requirements like autonomy, remote control or sensors? preferable, yes.
Given the budget and requirements, Ebram’s suggestions are likely the closest options. The Rover Robotics have great payload capacity and the two within your price range are the 4WD and 2WD. For example:
Water environment: IP67 rating
Payload: 180 pounds (~80Kg)
Budget: $6925 USD
Processor: You choose
Tracked / Wheels: Why not both?!
Without additional details / requirements, this seems to meet all of your needs.