MRQ-A is a pyramid rubber wheel chock with an aggressive tread, 3 cavity base. Pyramids allow for ease of placement, and drop-kick safety. It has the highest weight to power ratio of any other pyramid model. It?s a light chock with good performance. Tire Size: Large Tires (3 Cavity) % Grade Rating: 9.5% (19% Paired) Test to Failure: Meets SAE standards (paired) Best Use: Wide variety, general use.