Own '95 GL1500 sidecar rig almost 13 years. Learned thru use: Metzler 880 Marathon REAR tire has weaker sidewall than Avon Venom, so stuck with Venom[front & rear]until switching last riding season to Austone rear tire[SUPER tire for our rig!]. Venom rear tire was TOO WIDE to fit in my swingarm. Avon widened it over previous Venom and it rubbed on right inside of swingarm. Austone is a God-Send! My two cents.
.....papasmurf P.S. Still run Avon Venom FRONT tire, as it handles well on our rig.
As long as you're using a tire that's rated properly for the bike, the most important thing is to run the correct tire pressure. I believe most of the common tire problems start with improper pressure...and some of them don't show up until later in the tire's useful life.
But.... some have run the GL1800 radial on the front without a problem(was put on at a dealer unknown to the purchaser)
I have toyed with putting one on the front as I am Darkside radial on the back anyhow(for more weight capacity and longevity as well as superior handling)