I have a 2002 Explorer XLT. I get a noise from the rear end which sounds like a rotational whine when I take my foot off the accelerator. Vehicle also seems to surge too. The only time the problem happens... Engine temp has to be normal operating temp. I exceed 42 mph (anything below that speed won't generate the noise.) Once the noise starts, it continues under 42 mph as the vehicle slows. There are no OBD warnings. One thing that my be of issue.... I have two different pairs of tires. both pairs are the same size tire. back pair are different brand than the front pair. Rear tires have an off road pattern, fronts are more car tire. Transmission is not slipping. I'm a DIY'er and not sure where to start. Thanks.