I have a 2016 Thor ACE 29.4 on a Ford F53. I was underneath the other day greasing some fittings. While underneath I crawled around just inspecting. I noticed that the I had some type of fluid coating the inside rim of the real wheel passenger side. I'm guessing brake fluid but wondering if it could be something else. I tried to check brake fluid level but that seems impossible. Brake fluid reservoir is mounted very high and just enough room to get the cap off. I can't read the level because of the location. Thanks in advance for any input.