As I recall it was a potential problem on the venerable BAC 111. The system as I recall used the parking brake pressure line to apply brakes after gear retraction. If the parking brake set light remained illuminated after gear retraction there was a procedure to use try remove this pressure. My BAC systems memory is alittle hazy after 15 years. The BAC 111 had brake temperature gauges though and I once recall the brakes being on and the need to lower the gear because of excessive (or so I thought) heating of the brakes, tires, and all that other other stuff in the wheel wells. I seem to recall a 727 (Mexicana?) that suffered an inflight loss of hydraulic pressure due to tires exploding in the wheel well becase of extreme temperature. The 737- 200 (the entire family probably) does not have enclosed main landing gear. The tires and brakes are subsequently cooled by the slip stream with the aid of a hole in the wheel covering. The B737-200 also does not have brake temperature gauges. The way around knowing whether the brakes a cool enough for takeoff is to consult a brake cooling chart.