It has been forever since I was in the shop located at South Shore; as I recall it was pretty close to Ski Run. I wasn't impressed with the place, and the grapevine tells me it went under, anyway.
Strictly Scuba is probabally your best bet if you are diving the south-east and south shores of Lake Tahoe. They use PP blending to make gas, so the air is oxygen clean. It's a smallish shop, like all LDS's in the area. Be aware you will have to drive over Spooner Summit, about a +1000' excursion, so plan your exposure appropriately.
If you are diving the North side of the lake, including Sand Harbor, Reno is faster than Carson City. Either Adventure Scuba or Sierra Dive Center are good shops (although Adventure is closed this, not next, weekend until after the 4th of July). Tropical Penguins, well, any port in a storm I suppose, if you pay for immediate on-the-spot goods with cash you should be okay.
If you drive to Reno over Mt. Rose, it's about +2500'. This route is popular with folks diving Sand Harbor or the northeast shore.
If you are diving Sand Harbor, it's actually a wash between Reno and Carson City, the rest of the north shore though, Reno is your fastest.
West shore, including Rubicon, believe it or not, I'd go back to Reno via Truckee. A popular dive spot on the west shore, the Alley Cat at Hurricaine Bay, is 75 minutes from Reno, and D.L. Bliss State Park is about 10 minutes further. Returning via Truckee is no elevation gain.
Anytime you have to circumnavigate the Lake you are asking for a long delay, especially on weekends.
Have fun and enjoy! Might I add, bring a dry suit....
All the best, James