Marbmarc

Good Morning everyone, I hope everyone is well. I just have started to road bike and have kind of created a liking in this form of daily exercise.
I have a Schwinn mountain bike and I am not quiet ready yet to make the investment for a road or triathlon bike yet. I would like to replace the
rough off road tires with more suitable street tires and tubes. The dimension I took off my present tires reads 29x2.25/54-622. Which size of
road tires can I purchase to still fit the existing rims to get a smother and less width type of tire?

Gconan

700c . Here are a couple of brands. ReneHERSE cycles

Continental

WTB

The local Bike shops can help. They probably have tires in stock.

Marbmarc

Thank you. That helps. I just try to stay away from any unnecessary shopping trips. Furthermore I do live in the "country"
and I think my closes bike store is about 2 hrs driving time away.

Iride01 

The 54-622 is the important measurement to know. This is representative of the ISO or older ETRTO standard that tells you the width of the tire, 54 mm. The 622 mm is the BSD or bead seat diameter. Your rims will also have a BSD of 622 mm and will only fit tires that have a 622 BSD. So if you look for tires based on the 622 BSD then you will stand a decent chance of getting one that fits properly.

Sometimes the ISO is prominently displayed on a tire, but other times it's stamped or embossed in the tiny print you see along the side wall. I've never seen tires that didn't have it, but I haven't seen all tires. Occasionally they'll bastardize the numbers and it will be something like 700 x 25C or 25 x 700C. You just have to know that 700 represents the very old tire sizing for 700C which is also a 622 BSD.

HTupolev

As Iride01 says, 54-622 means the tire has a bead seat diameter of 622mm and a nominal inflated width of 54mm. In order for a tire to be mounted to a rim, the bead seat diameter must match exactly between the tire and the rim, so your new tires need to also have a bead seat diameter of 622mm. A bead seat diameter of 622mm is often marketed as 700c for road tires or 29" for MTB tires.

Tire width does not need to match exactly, although you might not want to drop all the way to a super-skinny road tire. Your MTB rims might not be designed to handle such a narrow tire - generally for safety you want the tire width to be significantly higher than the internal width of the rim bed - and its corresponding inflation pressures. A very skinny tire may also have weird effects on the bike's handling.

Inner tubes don't need to match a tire exactly, but it's good practice to not be crazy far off. Generally it's much easier to install a too-narrow inner tube than a too-wide inner tube: if you switch to narrower tires, you'll probably want to buy some narrower inner tubes as well. Make sure to buy the correct valve type (presta or schrader).

One classic affordable tire for this kind of build is the Panaracer Pasela. The 35mm or 38mm 700c models might be good options here. I'm a fan of the basic version with the red-and-yellow label. Paselas also comes in a "PT" version with a blue-and-white label which adds a puncture-protection belt under the tread; puncture-protection belts obviously help protect against punctures, although they can also make a tire a bit slower and less supple.

Marbmarc

Thank you so much for your elaborate response. Things are starting to make sense. With best regards and be well.