the cooler the weather, the more they drop!...but 13 lbs? Yikes!...do you need a bi weekly email reminder?
My Kymco (with 16" wheels) is a dream to check and fill the tires...back wheel can be spun on centerstand and front has very little weight on it so can also swing it around by hand to get valve access.
My Helix? That is awful. Back 10" wheel is blocked on both sides ...put kneeling pad on ground and kneel in back on swingarm side. Air pump nor tire gauge will not fit directly on valve so I attach a 6" extension to it, first, then can check or fill off that.
Front is almost worse. It has a straight valve stem (shop claimed they were out of 90 degree stems at tire change time)...can't get air pump on it or the extension I use in back. I first have to SCREW on a little metal 90 degree extension....sssssss as I screw it on, check air, fill, and unscrew to remove..ssssssssss....no idea how much air escapes so I have to slightly overfill and hope I unscrew it fast enough to not lose too much air.
I still check before each ride as my rides seem to be many days to weeks apart, anymore..