Thanks for the prompt reply.

The water in gas thing had me thinking and the only significant event that happened recently was the ECU warning light that lighted up last week but then went away.

I never got to the bottom of it but it did correspond to the day after I changed from premium RON98 to normal RON98 (no additives) maybe I also got water in the fuel from condensation in the pump tank (not from rain), this is a lot of speculation. What fuel do you use?

Apart from that I'd had to blame the dealer for something not well tightened during the 3rd-year revision 2 weeks ago, but I can't fathom how the noise would go away if that was the case. I did bring the car up to the same speed after the noise stopped.

it's probably the road

I do that stretch of highway many times. It was the first time the GT86 did it in that heavy rain, but I went through there again at night (still pouring) in a A3 and didn't notice anything out of the ordinary.

So, probably not.

I had the exact same thing happen to me. Thought I had a flat but the low tire light wasn't on. Pulled over and found a chunk of road tar on one of the wheels. Peeled it off and drove on with no problem.

the simplest explanation is usually the right one. So yeah g0odspeed probably picked up the road tar after you lol

Lol! More than likely!!