Pulsating Sound At Street Speeds

[00RX300-Again]

Hello, I just started getting a pulsating sound when I drive my FWD RX300 (115k miles) at normal street speeds (20-45mph). On the highway it doesn't seem to make the sound. I can’t tell if it’s a tire sound that just started or an exhaust sound or what it is. I have noticed that when I first start my RX in the morning the exhaust sound louder than when I’ve driven around a while (but not a pulsating sound). Has anyone else gone through this? Any ideas??

[Filehorse]

If the tires are getting old that can cause the sound you describe. It can also be caused by a failing wheel bearing. I had a similar issue with my RX300 and it turned out to be the tires. Replaced the tires and it was again as quiet as a church mouse. You also can't rule out a failing CV joint but with the limited information available, I'd be looking at tires first and then wheel bearings. Regardless, it "sounds" like you need to get it up on a rack where someone can do a real inspection.

[00RX300-Again]

Thanks for the reply. The tires are only about a year old with about 15k miles on them. They still look really good. I wasn't thinking it was a bearing or CV joint issue since the sound goes away at higher speeds (highway) and it dosen't change if I drive straight or around corners at lower speeds. There's no grinding or clunking sounds. Do you still think that it could be a bearing or CV joint?

[Filehorse]

Sounds are the most difficult thing to diagnose based solely on someone's description. As for the tires, I've thrown away at least one set of tires with only 15,000 miles on them because they were making the sound you describe. I hope you know a good independent shop who can help you diagnose what you're hearing. Oh, and the CV joint would probably not be on my roundup of the usual suspects but a wheel bearing could be. The pulsing sound you hear at low speeds can morph into roar and be masked by other sounds at highway speeds so don't discount that possibility. I'd still start with the tires and be looking for unusual and/or uneven wear patterns - often on the inside or outside grooves of the tire. You may need to swap some tires to see if the problem changes.