The trial court’s unappealed ruling becomes the law of the case, and we must assume the trial court was correct in ruling that a bicycle is not a vehicle. Resolution Trust Corp. v. Eagle Lake & Golf Condominiums, 310 S.C. 473, 427 S.E.2d 646 (1993). As such, Shives cannot be a Class I insured because none of Shives’s vehicles were involved in the accident. Instead, Shives is a Class II insured; therefore, he cannot stack multiple coverages. Even if the bicycle is a vehicle under section 38-77-160, Shives cannot stack additional UIM coverage because an insured can stack UIM coverage only in an amount equal to the UIM coverage on the vehicle involved in the accident. Because there was no UIM coverage on the bicycle, Shives cannot stack. See Howard, 288 S.C. at 11, 339 S.E.2d at 504 (<HOLDING>); Ohio Cas. Ins. Co. v. Hill, 323 S.C. 208, 473
holding that the amount of coverage determines whether a vehicle is underinsured holding section 3877160 clearly limits the amount of coverage which may be stacked from policies on vehicles not involved in the accident to an amount no greater than the coverage of the vehicle involved in that accident holding that policy limits are not a defense to coverage and that policy limits define the amount of coverage holding that new mexicos uninsured motorist statute nmsa 1978 section 665301 1983 requires an insurer to offer um7 uim coverage in an amount equal to the liability limits of the policy and that the choice of the insured to purchase any lower amount functions as a rejection of that maximum amount of coverage statutorily possible holding that excess coverage in four policies was not triggered until primary insurer satisfied the requirements necessary to trigger the excess insurers coverage and paid the full amount of its limits