Update - I set up my Hed Jet Plus wheels with Continental GP5000 TL tires this weekend. So, spoiler alert, I got it done in the end. But, it was a total pain in the ass and my hands are all sore from trying to get these tires over the rims.
There are two big problems trying to mount them; first the tire is extraordinarily tight and the forces needed pull a bead over the rim are impossible to overcome without various tools. Secondly the tire slips over the rim so easily that as soon as you're working from one side to force it over a rim it'll move and undo itself on the opposite end. Say you pull the tire over the rim as far as you can, then with any other tire if you were to use tire levers or the Koolstop tire jack you'd have enough friction on the ends of the section that isn't mounted yet, that you can stretch the tire with tools and pull it over the rim without it undoing itself. But because this one is so slippery, one of the ends will start to move and undo already mounted tire sections. Those two things combined make this a total bitch to mount.
In order to prevent this slippage at the ends I decided to use zip ties to tighten a section of mounted tire agains the rim, so to force hold it tight to make slippage more difficult. Not at all perfect but it helped. In combination with a tire lever in one hand and the tire jack in the other hand I eventually got the tire mounted but it always took many tries and close to an hour per tire.
Once mounted, the tire is so tight both beads are in the middle channel of the rim and they'll prevent easy installation of the valve stem. Tightening it causes the bead to get pinched underneath resulting in a leak and the inability to inflate it. This took me quite a few attempts of trying to inflate it with a compressor, then trying to get the valve to be tightened enough without pinching, inflating again, etc. If I didn't have a compressor, no way I'd eventually gotten the tire installed.
If these wheels would be for training I would say it's not worth it trying to set them up with GP5000TL; they simply can not be fixed in the field. But since I'm using them for crit racing it should be OK. Planning to ride them on the road this week in sort crit type training ride to check everything is working fine. But damn installation was no fun.
Thanks for the report. I'm generally hearing that the GP5000TL is fitting tight, but I haven't had the opportunity to try them myself. That is a bit surprising on the HED rims, because they are one of the easier rims to mount tires on (in my experience - and when using the proper technique of using the dropped center channel in the rim bed). For what it's worth, I'm on some Boyd Altamonts now, and they seem to be good in this regard - but the GP5000TL still may be pretty difficult.
The trick I use when one portion of the tire keeps coming unmounted as you mount the other side is to use these little clamps
. Or something similar.
Greg Kopecky - Slowtwitch Tech Editor
Founder of Minimal Multisport Athlete website, blog, podcast, and Youtube channel: https://www.minimalmultisport.com/