Ronald Eugene Staley died while installing new tires on a road grader when a multipiece tire and rim assembly explosively separated. Goodyear manufactured the rim of the tire and the side ring; Bridgestone/Firestone, Inc. (Firestone) manufactured the lock ring. Staley worked for Brad'Ragan, Inc., a wholly owned subsidiary of Goodyear; both it and Goodyear were Staley’s workers’ compensation employers and thus immune from dam *1508 ages claims. In this diversity suit by Sta-ley’s estate, widow, and children against Firestone for negligence, defective design and failure to warn, the district court ruled for Firestone as a matter of law on the warning claim, and a jury found for Firestone on the remaining claims. Plaintiffs’ appeal alleges error in the warning ruling and various trial errors. For the reasons stated below we affirm the judgment entered for Firestone.
I
When he died, Staley had nearly completed the installation of six new tires on a road grader in Fort Carson, Colorado. Two Fish and Wildlife workers found Staley’s body lying face down about ten to twelve feet from the road grader some two hours after Staley had reported to his employer that he had two tires left to mount. The lock ring and the side ring of the multipiece tire rim assembly were found between the road grader and the body, with a hammer nearby. Staley died from trauma to the heart, which plaintiffs argued was caused when the lock ring exploded off of the rim assembly and hit Staley in the chest. There was no eyewitness to the accident.
Plaintiffs alleged that the multipiece rim was defective, unreasonably dangerous, and negligently designed because it had a tendency to explosively separate under foreseeable service conditions. They produced evidence that if the components of the rim were assembled without being fully engaged they might separate following the addition of inflation pressure. The rim lacked a warning, and they argued Firestone negligently failed to adequately warn of the hazards of the multipiece rims. Plaintiffs also asserted there were safer alternative designs that would ensure seating of components or include only one piece that could not separate.
Firestone’s primary defense was misuse, that Staley mounted the tire contrary to his safety training. Firestone introduced evidence that Staley signed a training record acknowledging his hands-on training and familiarity with the OSHA rim servicing regulation applicable to this rim and agreeing to comply with the OSHA procedures. The parties contested at trial the amount of Sta-ley’s training.
Firestone produced evidence that Staley’s employer published and distributed safety literature posters and manuals instructing and warning their tire servicing employees about the necessity of using a restraint when putting the multipiece rim together and standing clear during inflation, and of the danger of hammering on the rim. Firestone also offered evidence that on the Friday before the accident a wildlife manager observed Ssalvy hitting a rim with a hammer while inflating the tire, without restraining the tire and rim assembly. This witness testified that Staley said he inflated the tires to eighty-five pounds although the correct pressure would be no more than thirty or thirty-five pounds.
An OSHA report introduced into evidence concluded that the accident occurred because Staley failed to follow the mandated safety procedures. That report found Staley probably hammered the lock ring on the inflated tire and rim assembly and did not use a tire and rim restraint; it criticized Staley’s employer for not providing a safety cage and functional clip-on air chuck.
II
Plaintiffs assert that the district court erred in granting Firestone’s motion for judgment as a matter of law on plaintiffs’ negligence and strict liability claims for failure adequately to warn. We review a district court order granting a Fed.R.Civ.P. 50 judgment as a matter of law de novo, applying the same standard as the district court.
Lyon Dev. Co. v. Business Men’s Assurance Co. of Am.,
[a] failure adequately to warn can render a product, otherwise free of defects, defective for purposes of strict liability re *1509 covery. Hiigel v. General Motors Corp.,190 Colo. 57 ,544 P.2d 983 (1975). Under strict liability, the test is whether the manufacturer’s failure adequately to warn of the potentially dangerous propensities of its product rendered the product unreasonably dangerous. Union Supply Co. v. Pust [196 Colo. 162 ,583 P.2d 276 (1978)], supra. Should the manufacturer fail to give warnings of dangers inherent in the product or in its intended use sufficient to mate it safe, the product is in a defective condition “unreasonably dangerous” to the user or consumer. Hiigel v. General Motors Corp. [190 Colo. 57,544 P.2d 983 (1975)], supra; see also Restatement (Second) of Torts § 402A comment j (1965).
Davis v. Caterpillar Tractor Co.,
The district court found that defendant was not strictly liable for a failure to warn and had no duty to warn Staley because his employer understood the alleged dangerous condition posed by multipiece rims. The court relied on
Cruz v. Texaco, Inc.,
Plaintiffs argue that Colorado has not adopted this “knowledgeable purchaser” defense. Indeed, our research has revealed no Colorado cases specifically adopting or rejecting this defense. We agree with plaintiffs that
Kysor Indus. Corp. v. Frazier,
But even if the district court erred in its reliance on
Cruz,
Firestone’s alternative arguments for upholding the judgment on the product warning claim are persuasive. Plaintiffs did not show how an effective warning could have been placed on the thin lock ring, the only component manufactured by Firestone.
1
See Camacho v. Honda Motor Co.,
Ill
A
Plaintiffs contend that the district court erred in instructing the jury regarding product misuse. They argue the evidence did not support the giving of a misuse instruction under Colorado law and, alternatively, even if proper the instruction incompletely stated the law of Colorado regarding product misuse. '
In a diversity case the substance of a jury instruction is a matter of state law,
*1510
but its grant or denial is a procedural matter controlled by federal law.
Farrell v. Klein Tools, Inc.,
Firestone’s main defense at trial was that Staley failed to follow safety procedures when he mounted the tire and his failure to do so caused the rim assembly to explode. The alleged misuse included failure to use a tire and rim restraint and hammering on the lock ring of an inflated tire. Colorado has adopted
Restatement (Second) of Torts
§ 402A (1965), which “recognizes a defense for the manufacturer where the user mishandles or misuses a product and thereby creates a dangerous condition.”
Jackson v. Harsco Corp.,
There are three elements of misuse under Colorado law: (1) use in an unintended manner or for an unintended purpose, (2) the use was not reasonably foreseeable by the manufacturer, and (3) the misuse caused the injury.
See Uptain v. Huntington Lab, Inc.,
In the instant case, however, there was evidence of only one incident involving hammering on this kind of product. This contrasts with numerous instances of failure to properly clean a medical drill in
Schmutz, see
Plaintiffs argue that even if a misuse instruction was proper the instruction given failed to tell the jury that if it did not find misuse it could still consider Staley’s conduct in apportioning fault. The court’s instruction on misuse was as follows:
A manufacturer of a product is not legally responsible for injuries or damages caused by a product if:
1. The product was used in a manner other than that which was intended;
2. That use could not reasonably have been expected by the manufacturer; and
3. Such use rather than a defect, if any, in the product caused the plaintiffs claimed injuries or damages.
Appellants’ App. 134, 707. The pattern jury instruction in Colorado from which this came also included the following paragraphs:
*1511 If you find that all of these three propositions have been proved, then your verdict must be for the manufacturer.
(On the other hand, if you find that any of these three propositions has not been proved, you may still consider whether plaintiffs use of the product constitutes comparative fault, as that term is defined in these instructions.)
Id. at 167.
Plaintiffs argue that because the first of these unnumbered paragraphs was omitted the jury was not required to find all three elements before finding for the defendant manufacturer on misuse. But we read the inclusion of the word “and” in the instruction to indicate to the jury that they must find each of the three elements of misuse. Further, the instructions as a whole made clear that Firestone had the burden to establish the affirmative defense of misuse.
Plaintiffs argue that failure to include the second unnumbered paragraph was error because it did not allow the jury to consider comparative fault. They argue that Firestone at best showed Staley used the rim in an improper fashion rather than misused it. We need not decide whether there is a difference between misuse and improper use in this context. The evidence supported giving the misuse instruction, and the jury found all the elements of misuse. The permission given the jury by the omitted paragraph becomes applicable only if the jury finds one or more of the elements unproved. Thus, even if the court erred in failing to give this part of the instruction it was harmless. .
B
Plaintiffs assert the district court erred in giving an instruction on alternative designs because the instruction was not warranted under Colorado law and overemphasized a single element of the risk/benefit analysis. The challenged jury instruction was as follows:
Plaintiffs have claimed that there was an alternative design to the TG rim that was safer. For any design to be considered an alternative to the TG design, plaintiffs must show that the alternative safer design was practicable under the circumstances and said design was available at the time the TG lock ring was placed into commerce in 1973.
Appellants’ App. 706-07. Plaintiffs argue that although a feasible alternative is one factor to be considered in the risk/benefit analysis in determining whether a product design is unreasonably dangerous, it is not a required element. This instruction, however, was based on
Allen v. Minnstar, Inc.,
rv
Plaintiffs assert the district court made various errors in the admission or exclusion of evidence during trial, decisions we review only for abuse of discretion.
C.A. Assocs. v. Dow Chem. Co.,
A
First, plaintiffs argue the court erred in allowing the jury to consider evidence and argument regarding the negligence or fault of nonparties including the decedent’s employer (Brad Ragan, Inc.) and Goodyear. They cite Colo.Rev.Stat. § 13-21-111.5(3) which provides that negligence or fault of a nonparty may be considered “if the defending party gives notice that a nonparty was wholly or partially at fault within ninety days following commencement of the action unless the court determines that a longer period is necessary.”
Id.
After dismissing Goodyear from the case as a defendant, the district court granted plaintiffs’ motion to strike Firestone’s designation of Goodyear as a nonparty at fault because the designation did not identify the conduct that could provide a basis for finding Goodyear at fault. Plaintiffs argue that the designation requirement must be strictly construed, relying on the following statement from
Thompson v.
*1512
Colorado & E. R.R. Co.,
Requiring such strict compliance with the statute avoids a situation in which a named defendant reduces its liability by blaming a nonparty but a plaintiff does not have the chance to recoup that percentage of fault from the nonparty.
We hold that a court may not allow the finder of fact to consider the negligence or fault of a nonparty unless such issue has properly been raised by the defendant in a pleading which complies with the requirements of § 13-21-111.5(3), C.R.S. (1987 RepLVol. 6A).
The district court here refused to allow the jury an opportunity to apportion fault to Goodyear or Brad Ragan, but permitted evidence of their conduct to establish causation. We hold this is a proper distinction from the situation involved in
Thompson.
Firestone can only be held liable if its conduct was a contributing cause of the injury. It surely must be allowed to defend itself by showing someone else’s action or inaction was the sole cause of the injury. That is different from apportionment between two parties both of whose fault contributed to the injury. The jury instructions as a whole correctly set out Colorado law on causation, and we must presume that the jury followed the law.
United States v. Lane,
B
Plaintiffs assert the district court erred in excluding exhibits relating to the danger of multipiece rims and the safety and feasibility of the single piece rim design, and in denying admission of the emergency room record. The deference we accord a trial court’s discretion “is particularly fitting in lengthy trials including ... highly technical expert testimony.”
See C.A. Assocs.,
Plaintiffs argue that they should have been allowed to admit a 1958 magazine article characterizing multipiece truck tire rings as “killer” rings. 2 The district court did not abuse its discretion by excluding that exhibit because it dealt with truck tires, not grader tires, and its probative value was substantially outweighed by the potential for prejudice. Plaintiffs also asserted that the “Di Federico Memorandum,” which referred to the magazine article, was erroneously excluded. Our review of that memorandum convinces us it was not particularly relevant to the issue of use of multipiece rims for the off-road graders at issue in this case.
Plaintiffs also argue that the district court erred in excluding the emergency room record. They point out that there was inconsistent evidence concerning the external markings on Staley’s body; some evidence supported plaintiffs’ position that only a ring struck him, while other testimony supported Firestone’s position that the hammer struck Staley, indicating that he hammered on the ring. Plaintiffs note that the emergency room record indicated the contusions on Sta-ley’s chest were curvalinear, and thus was evidence that Staley was hit by a lock ring or side ring. But the contents of the report *1513 were presented to the jury by the doctor who performed the autopsy; she testified that the emergency room record and autopsy record both indicated a eurvalinear contusion. The district court did not abuse its discretion in excluding the record itself.
C
Plaintiffs assert various other errors by the district court in admitting evidence that they contend was either irrelevant or prejudicial. They argue that allowing lay witnesses Ross and Travnieek, the game wardens who discovered the body, to speculate about what Staley had been doing at the time he was killed violated Fed.R.Evid. 701 which provides “[i]f the witness is not testifying as an expert, the witness’ testimony in the form of opinions or inferences is limited to those opinions or inferences which are (a) rationally based on the perception of the witness and (b) helpful to a clear understanding of the witness’ testimony or the determination of a fact in issue.” We see no problem with the descriptions of the marks found on Staley’s body or the description of the size and location of the equipment at the scene. Although the testimony about Staley’s likely position just before the accident was somewhat speculative, it was not an abuse of discretion for the district court to allow that testimony.
Plaintiffs also assert that Chris Bandy’s testimony concerning Staley’s actions in assembling a rim on an earlier occasion violated Fed.R.Evid. 404(b). The district court limited the use of Bandy’s testimony to evidence of Staley’s plan or procedures and not as proof of a habit. Evidence of the procedures Staley used while working on the project on the last workday before he was killed was relevant, admissible evidence.
Plaintiffs contend that the district court should not have admitted the Occupational Safety and Health Administration (OSHA) investigation report because it was based on hearsay and was unduly prejudicial. Such a report may be admitted if the district court determines it is trustworthy pursuant to Fed.R.Evid. 803, and that its relevance outweighs risks of prejudice under Fed. R.Evid. 403.
See Beech Aircraft Corp. v. Rainey,
Finally, plaintiffs argue that the OSHA regulations concerning the servicing of multipiece and single piece rims should not have been admitted because they regulated the conduct of Staley’s employer and not Staley. Firestone points out that Staley was trained and instructed concerning the regulations and had agreed to comply with them and thus the OSHA regulations were evidence concerning foreseeable misuse.
Cf. Canape v. Peterson,
V
Finally, plaintiffs contend that the district court erred in denying their for cause challenge of juror Jerry R. Perez. During voir dire Perez stated that he had worked with multipiece rims and had used protective cages while working on tires. Plaintiffs argue that because Firestone’s entire defense was built on a claim that Staley failed to follow proper procedures in servicing the multipieee rim, including not using a restraining device, Perez’ close connection to similar facts rendered him biased.
*1514
“Generally, a court must grant a challenge for cause if the prospective juror’s actual prejudice or bias is shown.” Vas
ey v. Martin Marietta Corp.,
AFFIRMED.
Notes
. Plaintiffs produced evidence that Goodyear— which manufactured the other two parts of the multicomponent assembly—probably could have put a warning on those parts; but Goodyear is not a defendant here.
. Plaintiffs rely on
Jackson v. Firestone Tire & Rubber Co.,
