At the outset, we note that the act of alleged negligence which the plaintiffs contend caused damage to their truck occurred in North Carolina. The accident occurred in South Carolina. South Carolina law governs as to whether the defendant is liable for the alleged negligence. See Chewning v. Chewning, 20 N.C. App. 283, 201 S.E. 2d 353 (1973). We believe the law of South Carolina governing liability for negligence is the same as the law of this state so far as the issues are concerned in the case sub índice. See Mahaffey v. Ahl, 264 S.C. 241, 214 S.E. 2d 119 (1975) and Smith v. Fitton and Pittman, Inc., 264 S.C. 129, 212 S.E. 2d 925 (1975). In this opinion we do not distinguish between the law of the two states in applying the principles of liability for negligence to the evidence in the case sub judice.
[1] The plaintiffs have offered evidence from which the jury could find that at the time the tire and inner tube were installed on the plaintiffs’ truck, the inner tube was too large for the tire and this caused the tube to fail which was the cause of the *381“blowout.” From this we believe the jury could find the defendant did something which a reasonable man would not do and this was a proximate cause of the accident. It was error to grant the defendant’s motion to dismiss the action. See 9 Strong’s N.C. Index 3d, Negligence § 1 for a definition of negligence. The defendant contends there was not sufficient evidence in the record to support a finding that the defendant installed the tire and tube. Mr. Chestnutt testified the truck was carried to the defendant’s place of business on 14 March 1975, and the tire was installed. It stayed on the truck until the date of the accident more than three months later. This is evidence from which the jury could find the defendant installed the failed tire and tube. The defendant also contends that the testimony of Mr. Cerny that the tube was too large for the tire placed no responsibility on the defendant. We believe it is a jury question as to whether the defendant, who was in the business of selling tires, acted as a reasonable man in that business in installing a tire with a tube which was too large. See W. Prosser, Handbook of The Law of Torts, § 32, p. 161 (4th Ed. 1971) for a discussion as to the duty of a reasonable man with superior knowledge in a certain trade.
[2] The defendant also argues that the plaintiffs failed to establish a causal connection between the action of the defendant and the accident in question. On cross-examination Mr. Cerny testified he could find no puncture marks on the tire but if there had been a puncture on the part of the tire he was not able to examine, this could have caused a loss of air. He also testified that driving on the tire while it was underinflated or if the truck was overloaded could damage the tire. The defendant contends these answers on cross-examination leave it to the jury to speculate as to the cause of the failure of the tire. We note that the expert witness testified that in his opinion, the creases in the tube caused the tire failure. This answer was struck on motion of the defendant and the witness was only allowed to testify that in his opinion the creases could or might have caused the failure. It appears that we have a case in which the witness was not allowed to testify to the degree of certainty which he had as to causation and the defendant then moved for dismissal because the witness was not certain enough. See 1 Stansbury’s N.C. Evidence § 137 (Brandis rev. 1973). In Mann v. Transportation Co. and Tillett v. Transportation Co., 283 N.C. 734, 198 S.E. 2d 558 (1973) Chief Justice Sharp indicated that it is *382proper for an expert to be allowed to conform his answer as to causation to his true opinion. We hold it was error to strike Mr. Cerny’s answer that, in his opinion, the creases caused the tire failure. We believe it was a question for the jury as to whether the other possibilities raised by the witness’s answers on cross-examination were the causes of the failure.
[3] Henry W. Denby appeared as a witness for the plaintiffs. He testified he was a truck driver and was riding with Mr. Chestnutt at the time of the accident. He also testified that he checked the right front tire before he began the trip and it did not appear to be flat. He testified further: “It was not leaking air.” On motion of the defendant, this statement was stricken. This was error. We believe the jury would have no difficulty deducing that this was the witness’s shorthand way of saying that from his examination of the tire, he could not determine that it was leaking. This testimony tended to prove that the tire was full before the failure and was relevant to the issues involved in this case. The defendant contends the witness could not testify to this matter without being qualified as an expert. We do not believe a witness has to be an expert to testify as to whether a tire is leaking.
The appellants have not assigned error to the dismissal of their claim for breach of warranty. We affirm the dismissal of this claim.
We do not discuss the matters brought forward by the appellant’s other assignments of error as they may not recur at a subsequent trial.
Reversed and remanded.
Judges Hedrick and Hill concur.