About 15 deg is when I move from shorts to tights, 10 to shorts over tights. Forgot the shorts today in 5 deg, and by God I was wishing for windproof jocks.
I am the bloke who does most sessions on the rollers in tights and a long sleeve, and keeps a beanie and fleece on until I get a sweat on, so perhaps my opinion is not the best to be listening to!
Like many others, never!
If youāre ditching shorts, itās too cold to run outside.
Also, for some men, shorts over the top of tights should be compulsory. 
Oh man, you should chat to my in-laws, or indeed one of my wifeās mates from school (with a lazy 8:15 PB). They wouldnāt be able to get outside and run six months of the year!
Under 5C to start considering along with maybe long sleeve top but if nice weather would still wear t-shirt and shorts. If on the moors in the rain and wind would consider between 5-10C. Cycling I tend to wear my running tights over my bib shorts once itās around 10.
Used to regularly run with a buff, but tend to leave that as well now.
I often start with a buff on then take it off and wrap it round my wrist if I get warm.
Theyāre so versatile.
You start in the buff?? Knew you northeners were hard as 
And then wrap it round our wrists. Donāt want it dangling in puddles.
-10 today in the snow. Trail shoes, ski socks, merino tights, shorts over tights. merino base layer, wind proof gillet, buff and running gloves. Nice and toasty
Similarly nice run today in long tights in snowstorm and settled snow generally between 3 and 6 inches deep about 1300ft up.
Noticed if I donāt wear in cold weather I get knee issuesā¦donāt think the 56 year old knees like being cold!
Ps gear included innovate trail shoes (over fell shoes today) dhb socks leggings 2 hellys buffalo mittens helly balaclava helly hat race buff and omm windproof waterproof top. Also new 15 l Montagne rucksack and loads of spare gear. Felt like Arctic Expedition saw no one or no car only out about 2 hours heaven.
try 57 year old kneesā¦
I put my tights on late August and take them off early Juneā¦
I can hardly wait !
I wear thin tights if it gets frosty. I generally run hot - it would have to be properly Baltic to wear anything warmer than a long-sleeved base layer on my top half - but I reckon my legs work better without the warmth being continuously whipped away from the skin.
Iāll be going out shortly in baselayer, 3 more layers of merino, windproof jacket, neck buff, head buff, hat, tights, with 3/4ās over the top, might add a couple more layers to the top.
I was just about to head out and saw that it was -6 and a skating rink out there. Zwift time for me and a run if it defrosts later.
Jesus Christ!!
do I detect an element of sarcasm here?
NO! That is what I wore, well actually I couldnāt find a hat so it was double buff on the head one twisted as a hat, and I wore the rainproof jacket not just the windproof one. Oh and I only added one extra layer above the wool although that was quite a heavy layer.
It was 0.0 on the outdoor thermometer, although I didnāt see a single bit of ice on the ground
fuck me - Iād be sweating like a glassblowerās arse before stepping out of the door wearing that lot!
even in sub-zero temps my running gear would max out as shorts, long sleeved baselayer, windproof front gilet, windproof gloves and a thin hat or buff. might be cold to start out but Iād soon warm up and be quite toasty.
On the hills yesterday - compression shorts, compression tights, socks, trail shoes, base layer, long sleeved layer, buff, hat, gloves, over mittsā¦and i was still coldā¦
should have worn my waterproof socksā¦
I donāt own that many running clothes, let alone wearing them at once!