On Thursday, July 7, 2016 at 3:21:21 PM UTC-6, Dave Springford wrote:
On my way home from Nephi (towing my trailer with the RV) I stopped for fuel and found one of the bolts that holds the Al-Ko trailer tongue together was gone as can be seen in the picture he

http://www.foxonecorp.com/images/20160703_154501.jpg

In the picture you can see the front hole that has been vacated by the bolt. Fortunately, the second bolt didn't fail before I stopped for fuel and also fortunately, five minutes down the road was a well stocked hardware store. So I was back on the road an hour later.

The original bolts are M12 x 100 with an 8.8 rating giving a tensile strength of 800 MPa (116,000 PSI). The holes in the tongue will accommodate a 1/2 inch bolt so I installed 1/2 x 4 inch grade 8 bolts with a tensile strength of 150,000 psi.

These imperial bolts are about .02 inches larger in diameter than the M12 and also about 30% stronger, not including the added effect of the extra diameter.

I emailed with Alfred Spindelberger and he indicated there is no harm in using stronger bolts.

So... my suggestion to those that tow their trailer with an RV is to check the bolts on the tongue, and maybe just go ahead and replace them before yours fail. It also might be a good idea to replace them every 4-5 years if you tow a lot with your RV (my trailer was new in 2012). Then, keep a spare set of 1/2 x 4 grade 8 bolts in the trailer just in case.

A few dollars in bolts might save you thousands in repairs!

Now, at every fuel stop, as well as visually checking tires and wheel hub temperature on the trailer, I'll also be checking the bolts.

Just went and checked my bolts on my 2006 Cobra trailer. Mine are original and they are 10.9 grade. Pulled behind my motor home with many miles....no problems....yet...thanks for the pictures and glad it turned out safe.

Best. #711.