A party may serve upon any other party a written request for admission of the truth of discoverable matter. See TEX. R. CIV. P. 169(1) (former rules - Effective January 1, 1999, rule 169 was repealed and replaced by rule 198. We apply the former rule.). If the party to whom the request is directed does not respond within thirty days after service, the matter is admitted without the necessity of a court order. See id. "Any matter admitted under this rule is conclusively established as to the party making the admission unless the court on motion permits withdrawal or amendment of the admission." TEX. R. CIV. P. 169(2) (former rules). Deemed admissions serve as evidence in lieu of the testimony of witnesses. See: Taylor v. Lewis, 553 S.W.2d 153, 161 (Tex. Civ. App.-Amarillo 1977, writ ref'd n.r.e.) (op. on reh'g); Red Ball Motor Freight, Inc. v. Dean, 549 S.W.2d 41, 43 (Tex. Civ. App.-Tyler 1977, writ dism'd w.o.j.) (noting admissions made by parties in response to request for admissions under rule 169 and filed among papers in case need not be introduced in evidence to be properly before trial and appellate courts); Insurance Co. of N. Am. v. Fire Ins. Exch., 508 S.W.2d 703, 704 (Tex. Civ. App.-Waco 1974, no writ) (noting "better practice" to offer admission into record but admission "properly considered" where filed with clerk and part of record at time of trial).