front left tire noise

'93 4Runner 170K Just wondering if someone could help me... for about a week I've been hearing a strange whirring noise coming from the front drivers side wheel area. I only hear it when at freeway speeds above 60mph and also only when decelerating or keeping a constant speed... I looked at the tire but it seems to be wearing OK, never had the bearing replaced... think it might be a wheel bearing? Maybe I should start by rotating the tires? TIA John