Driving a 2005 Hilux (KUN26 frame, manual diesel), I recently started hearing a soft rustling periodic noise seemingly coming from the front-left side (could be the wheel/tire). It feels like as if the tire was a bit uneven/damaged or with low air pressure. The period pretty much depends on the speed: I counted the number of noise cycles per known road distance and the period appears to be roughly 6.5m.
However, the tire diameter is 31" which makes the circumference roughly 2.5m long only, so I cannot see how it would produce a noise with 6.5m period. Then, all 4 tires looks good to me.
The noise started after driving several hundred kms since installing new tires, doing wheel alignment and changing all gear oils. Does anybody have an idea where the noise might be coming from?