Haul roads are designed to bear dynamic truckloads generated during haulage. Current road design methods consider static truckloads, which are lower than dynamic loads. They are also unreliable for designing roads for ultra-large trucks. This paper introduces a methodology for designing roads using dynamic loads for any haul truck. A 3D rigid multi-body dynamic virtual model of CAT 797F was built, verified and validated in MSC.ADAMS to model truck tire dynamic forces generated during haulage. Maximum dynamic forces were 2.86 times static force at rated payload. Industrial useable models that capture truck dynamics are proposed to improve road structural design.