tire chains

We are flying into Fresno the first weekend in November and renting a car. 1. Where is the quickest place to stop and buy tire chains since we must have them to enter Yosemite? 2. Will there be someone we can pay to put them on should we need them? (we have never used them) We are staying in Yosemite 3 nights before driving to Vegas. I know Tioga Pass would be our best route if still open, but what about it is not still open? 3. Any suggestions other than those I have read which involves going back to Fresno then on to Bakersfield, etc?

Tire chains can be purchased many places. I purchase them at
auto supply stores. In California, we have Kragen and AutoZone.
You will need the tire size of the rental car to purchase the
correct size.

You will probably see an auto store while driving around. Or you can
look them up in the phone book.

With the chains, I generally buy tensioners. They are large rubber
bands that keep the chains tight. They tend to prevent damage
to the car's wheel well.