Desser 850's are treadless-- maybe you're talking about Airtracs?
I've heard you state many times that GY 850's are larger than Airtracs.
The Desser-recapped GY 850's on my airplane now don't seem noticeably larger than the Airtracs.
When I get them off, I'll have to compare the size & weight in comparable conditions (off the wheel).
Also, I prefer the rounded profile of the Airtrac's, and I've always gotten good service life from them.