Get rid of the cr@p tires on your trailer!!! And I don't just mean replacing the belted tires with radials. I know a lot of you guys have been doing that, and most of you have been getting new radials for free, but IN MY OPINION you're still running a risk of tire failure. And possible boat damage. These Yamaha's are ~$60k boats, do you really want to be towing that investment on $39 tires? YIKES!!!
Ok so here's the story... Shoreland'r specs the trailers for 14 inch radials. The Yamaha dealers want to make every last dime they can so they buy the cheapest 14" tires and wheels they can buy. You can buy the tires AND wheels on these trailers for about $60 each. Seriously. Your $60k boat is riding on $240 worth of wheels and tires. Seriously? That's insane. Again, this is my opinion.
So I started looking at a solution. The highest load range you can get in a 14" trailer tire is load range C. That's 1870lbs MAX. EACH. So your 242 weighs around 6k lbs wet. That's 1500lbs on each tire IF everything was perfect and each tire was loaded perfectly evenly. So 1500lbs on a Chinese tire that's rated for a max of 1870, some would say that's "ok". But in a real world, those 4 tires are very rarely loaded evenly. So what happens when you have 4k lbs on one axle and 2k on the other? You now have 2000lbs on a Chinese tire that's "rated" (debatable) at a max of 1870. That's a problem.
So after researching tire and wheel sizes and weight ratings, here's what I found... You really need to have 15" wheels on these trailers. When you go to 15" wheels, you can then go all the way up to load range E or 2830 lbs max each. Load range E is a little overkill in this application, load range D is plenty. Load range C is too low though and really doesn't give the situation any wiggle room for overloading or uneven axle loading. (More common than you'd think.) The stock size on these Yamaha/Shoreland'r trailers is 215/75/14. I settled on 225/75/15 load range D as what I would call the perfect size and load range. That size tire is rated at a max load of 2540 lbs each. That's a total load range of 10,160 lbs. for a tandem axle trailer. Sound like overkill? Not really. That 10,160 number on a tandem axle trailer is actually supposed to be reduced by ~15% or so over a single axle trailer. So the max load range is more like 8700 lbs or so, or 4350 per axle. That gives enough overhead so that if there's 4000 lbs on one axle and 2000 on the other, it's still ok and safe.
So what do all those numbers mean? It means that if you want to drastically reduce your chances of being on the side of the highway with a blown out tire and possibly damaged trailer/boat, get those undersized wheels and tires off your boat now!!! Seriously.
Here's some pics of the wheels and tires I got. I bought them from Onlinetires.com. The guy I dealt with was Leonardo Garcia, a really nice guy that took good care of my order. The original wheels I ordered weren't available, he found some wheels that actually looked better and asked if I wanted to switch the order to them. I did and he had them mounted and balanced before shipping them. I literally unwrapped them when they got to my house and put them on the trailer. Super easy. They cost me a little over $800 including tax and shipping, mounted and balanced with new lugnuts even. The tires I got were Maxxis 8008's, they seem to be THE trailer tire right now. They tow great, fit perfectly and I now don't have to worry about cheap overloaded tires ruining my weekend or trip.
As far as fit, on MY trailer they fit perfectly with no rubbing whatsoever. What I did do though is to cut the extra threads off the two bolts that are directly above the tires though. You can either cut them shorter, or simply flip them over and have the nut and threads on the top side of the fenders instead. The 15's look awesome on these trailers and the particular wheels I ended up with look WAAAAAYYYYYYY better than the cheap stamped steel stock wheels. DO IT! lol.