Rich, Another cause of the sidewall cracking is due to deterioration as a result of extended exposure to sun. If you notice, those owners of the expensive RVs typically have tire covers. One side usually gets more sun exposure then the other, which sounds like what has happened to your trailer. When I took ownership of my M-15, I too had to replace cracked tires. As others have stated, it's cheap insurance. Good Luck, Skip -----Original Message----- From: speedernut2 <speedernut2@gmail.com> To: For and about Montgomery Sailboats <montgomery_boats@mailman.xmission.com> Sent: Tue, Sep 24, 2013 8:12 pm Subject: Re: M_Boats: Trailer Tire Sidewall Cracks Rich, Those little guys deserve a decent burial. I'd bet they are 15 years old at least. Hard to justify changing them when you only run 50 miles a season, but I think I would replace them next spring for the cheapest rubber I could find that fit. Mike -----Original Message----- From: Rich Makela Sent: Tuesday, September 24, 2013 6:00 PM To: For and about Montgomery Sailboats Subject: M_Boats: Trailer Tire Sidewall Cracks I've noticed cracking on the sidewalls of my M-17 trailer tires, and I'm trying to determine whether it poses a threat. I've attached a PDF with photos. The starboard tire is worse than the port tire. I can't find the code that is supposed to tell me the date of manufacture. They are both Reynolds bias-belted tubeless tires. I only haul the boat from the lake to my home, and then to storage - less than 50 miles total. I've found information on Goodyear web site about RV tires stating that sitting around and not moving can cause sidewall cracking. Can anyone out there with tire experience offer any advice? Thanks. Rich Makela M-17 #233 - Harmony