My driveway is short, paved, with about a 1/8 mile climb that peaks at about 16% slope (only a couple dozen yards), and gets a moderate dusting of fir needles (which I'm not knocking off quickly enough now that I stopped driving).

When wet, I loose traction.

I've found that I can use it as a qualitative judgement for tire traction.

I'm hoping to eventually get setup for a quantitative traction assessment, but I'm not quite there yet.

It is a tough course for a road tire. I can either climb the hill standing or sitting, and either on my Colnago Super, or my Litespeed (or other bikes).

The Colnago has a relatively short wheelbase for a late 1960's model bike, and the gearing only supports a standing hill climb. The Litespeed has a relatively long wheelbase, and I can climb either standing or seated. This actually makes a significant difference in weight distribution, and correspondingly traction. Unfortunately, wheels aren't interchangeable between the bikes. 126mm vs 135mm. The Litespeed is the one that got the Tannus tires.

Standing, one also tends to throw the weight forward, off of the rear wheel, and have more abrupt power bursts, and correspondingly less traction. Sitting one gets more weight on the rear (sometimes to the point of too little weight on the front, with 100% of the weight on the rear), and a bit more even power, but I run at fairly low cadence, so it is still a pretty harsh power cycle.

The fir needles and wet conditions both contribute to poor traction.

I only have a few data points with different tires.

Schwalbe Marathon Plus 25mm. This tire has a moderate, relatively fast wearing tread, and by far has the best traction. I mainly rode it on the Colnago, and could make it up the hill standing. It would break loose periodically, but I would retain about 50% traction as the tire would spin.

Origin8 Elimin8er, 25mm, balding. Lots of trouble with the standing hill climb (Colnago). It would spin like on ice for a complete half crank revolution. However, on the Litespeed, it would generally be ok for a seated hillclimb.

Panaracer Pasela, 25mm. Tire had light tread when new, and eventually wore pretty bald. Mainly ridden on the Litespeed. Bad for standing hill climb (on the Litespeed), but generally ok for seated hillclimb. Overall, I would put it comparable to the Elimin8er.

Cargo bike with 20x4 1/4 rear tire. Very long wheelbase. Minimal tread. That bike also has quite a few problems on the hill, especially if towing. So, just wide doesn't make it better. With a light rear load, weight distribution is somewhat off of the rear tire.

Tannus 23mm solid tire (only testable on the Litespeed). I'd put this by far at the bottom of my list for road tires. It is the only tire that I started noticing an audible (and felt loss of traction) squeak/chirp with seated climbing under moderately wet conditions. Usually with the moderate wet conditions, it does regain traction and I can continue. However, under severe wet conditions (currently raining, or just after a heavy rain storm), I spin when seated, and end up unable to continue, and walking the hill.

The store incident.
Flat grocery store parking lot. Wet conditions (after rain, but not raining at the time). I pulled on the lot on private drive, then turned left between rows of parked cars at about 8 MPH. STRAVA choked at that moment, so data is jumpy. A car cut across rows directly in front of me. I think I only hit the rear brake with moderate pressure. I may not have hit the front brake. This induced both a skid, and a sidways slide with the rear wheel of the bike.

So far, I haven't had any traction problems on any other hills, standing or seated.

Needless to say, I am a bit leery about high speed wet cornering, and haven't had any issues yet.