These cases arise from motor vehicle collisions that occurred in 1992 and resulted in the imposition of merit rating surcharges on two of the insured owners of the vehicles by their insurers under G. L. c. 175, § 113B. The insureds appealed, pursuant to G. L. c. 175, § 113P, to the Board of Appeal on Motor Vehicle Liability Policies and Bonds (“board”) which upheld the surcharges after hearings. See 211 Code Mass. Regs. § 88.03 (1986).2 Both insureds filed complaints for judicial review under G. L. c. 30A, § 14. In two substantially identical rulings, the cases were remanded to the board by a Superior Court judge who determined that the board erred as matter of law in its treatment of regulatory presumption of fault standards. The board appeals, denying error and claiming its decisions properly were supported by substantial evidence. We agree with the board, reverse the Superior Court judgments, and affirm the board’s decisions.
Embodied in the board’s regulations establishing standards of fault to be used in determining the application of surcharges are several rebuttable presumptions. See DiLoreto v. Fireman’s Fund Ins. Co., 383 Mass. 243, 249 (1981) (The board may use its expertise in the determination of relative degrees of fault “in establishing presumptions ‘to serve sound social and economic policy through this method of controlling some of the procedural incidents of proof making.’ K. B. Hughes, Evidence § 42, at 48 [1961]”). The applicable regulations set forth operational situations in which fault is presumed to be in excess of fifty percent for the purpose of adjusting insurance rates and premiums. Involved in the present cases are regulations dealing with a vehicle that collides with another vehicle while making a left turn into the path of oncoming traffic and a vehicle whose operator fails to proceed with due caution from a stop sign. 211 Code Mass. Regs, § 74.04(8) and (15) (1986). Section 74.03, in force at the time of the accidents and the board hearings, provided that “[t]he presumptions . . . shall be considered determinative unless a showing to the contrary is demonstrated by the evidence presented” at the hearing before the board.3
In each of these cases the insured testified and the board in its decision stated that it “weighed the credibility of the [insured] as a witness against the evidentiary presumptions.” The judge apparently applied the “bursting bubble” theory of presumptions generally favored by our cases,4 and concluded that when any contrary evidence is presented to the board, the *916otherwise applicable presumption disappears, and is not available to be weighed against the credibility of an insured. In the cases before us, however, the wording of the regulation itself requires not merely the introduction of some contradictory evidence in order to overcome the presumption, but rather that a “showing” contrary to the presumption be “demonstrated.” See DiLoreto v. Fireman’s Fund Ins. Co., supra at 244-245 & 249 n.5, in which the court upheld the use of a presumption under 211 Code Mass. Regs. §§ 74.03 and 74.04, notwithstanding that the only evidence before the board was the insured’s testimony attributing inattention and unsafe speed to the operator of the other vehicle in the collision. See also Goddu’s Case, 323 Mass. 397, 401 (1948), and Lapinsky’s Case, 325 Mass. 13, 16-17 (1949), in which a statutory presumption has been permitted to survive contradictory evidence where the statute called for substantial rebutting evidence.
Macy Lee, Assistant Attorney General, for the Board of Appeal on Motor Vehicle Liability Policies and Bonds.
Brian T. O’Neill for Charles A. Smith.
We conclude not only that the board did not commit error of law, but also that there was substantial evidence to support its decision. See G. L. c. 30A, § 14(7); DiLoreto v. Fireman’s Fund Ins. Co., supra at 249 n.5 (“Since we uphold the presumption, we disagree with [the] contention that the board’s decision was not supported by substantial evidence”). It was within the board’s discretion to disbelieve the insureds’ versions of the collisions, see Embers of Salisbury, Inc. v. Alcoholic Bev. Control Commn., 401 Mass. 526, 529 (1988), in which event the presumption was to be given “determinative” effect. Accordingly, we reverse the judgments of the Superior Court and affirm the decisions of the board.
So ordered.