I have a schwinn bike, 30 years old. It ran great for 28 years, even tires didnt wear out. Last year tires had

to be replaced. Dealers couldnt match the same size tire as the bike had, but one very slightly narrower. I had no choice but to buy them, but air constantly leaks out slowly, once a week to put more air in. Where can I get Schwinn tires now?

The tires generally have nothing to do with leaking air. That is the job of the tubes.

Remove the tire and tube, check for spokes jutting through the rim tape and for sharp edges on tht rim. If necessary you can remove the old rim tape and replace with plastic electrical tape OR buy a new rim strip from your dealer.

While the tube is out, fill it slightly and immerse in water, bubbles will show if there are any leaks. Don't forget to check the valve... the most likely source of slow leaks.

Have you tried calling Schwinn or visiting their website?
http://www.schwinnbike.com/index.php

I have to put air(about 10-15PSI) in my tires about every ride, but then again i'm susceptable to lose air in my tires from pinching while mountain biking. I don't know how much air you're talking about losing. If it's completely flat, then yes, I agree, that is a problem. You should check out eBay. If it's 30 years old that's pretty crazy nice. Schwinn definitly doesn't build them like they used to, that being said I don't think Schwinn would be much of a help with finding these tires because of how much they've changed over the years, but it's worth a try to give em a call, but internet is your best bet and searching Local bike shops like crazy. I hope you keep that bike for another 30.

A 30 yr old Schwinn probably has 26 X 1 3/8 or 26 X1.75 tires. Those tubes are found at Wal-Mart, Target, and K-mart. Like mentioned before, you just need to change the tube and check for what made the leak in the first place. Check the inside of the outer tire, you may have a shred of metal, glass or even a thorn in the tire. If something is there, remove it when you replace the tube. If you are running on 30 yr old tires, you may want new ones to go with the tubes.

I'm not sure if Schwinn tires are available anymore. But tires don't leak - tubes do. I fill my tires weekly but I keep 110 PSI in mine. You don't say how much air leaks, replace the tubes, it's cheaper than tires and tires aren't the problem anyway.