A Mini-Tub is a modification that relocates the inner rear wheelhouses and frame rails inward to create clearance for wider rear wheels and tires. On a unibody car the factory wheelhouse and the frame rail beside it set the practical limit on rear tire section width; moving them inboard buys several inches of usable space without cutting into the quarter panel or flaring the body. The wider footprint raises rear lateral and longitudinal grip, which changes handling balance and usually calls for a matching front tire and spring revision. Mini-tubbing also affects wheel offset and backspacing choices, driveshaft and exhaust routing, and rear seat or trunk floor structure.