Hey all. I currently have a Nishiki Maricopa road bike and was looking into putting a more all terrain/mountain bike tire on it to start hitting the trails near me. Is something like this possible? My current wheel setup on my bike is
700c x 18c/23c.

Would I be able to use my current wheels and just get new tires? If so what size?

Thank you

Can you even fit anything bigger than a 28mm tire on that bike?

It's a road bike. If your talking gravel trails it may survive, but is not advisable. If your talking roots, jumps, tree hopping and etc., not a good idea.

I did this with one of my road bikes.

30mm Kenda Kwicks fit and made a real difference on dirt roads.

Your wheels will probably be OK with wider tires. You are on your own to determine what size will fit. Measure?

You almost for sure cant fit more than a 28mm tire in your frame. In the off chance that you can, it will max out at 32mm. This is based on your brake calipers and the brake bridge on the seatstays(where the rear brake is attached to the frame).

Depending on what 'hitting the trails' means to you, it could be fun or horrible on your bike. The geometry isnt made for trail riding. The tires and wheels arent made for trail riding. The fork isnt made for trail riding. The shifting and entire cockpit isnt made for trail riding.

If its pretty smooth hardpacked dirt, then it could be fun to ride with 28mm tires. Tough and jarring at times, but fun.
If the trails are rooted and have obstacles like logs and rocks as well as tight turns and quick inclines- it could be no fun.

I take my gravel bike(drop bar) with 40mm tires to a local forested singletrack sometimes and have fun, but it beats me up more than my mountain bike. Also, the gearing on my gravel bike is better for dirt trails than your Nishiki and 40mm tires help a lot for both grip and softening bumps.

Your bike isn't going to fare well on anything that would qualify as real mountain biking in my book. You can ride some fire roads and gravel without too much trouble though.

A mountain bike is a really good idea for this.

I looked at some pictures of the bike. From what I can see there is very little extra clearance with the stock 700 x 26 tires. This means that you would be unlikely to be able to get anything wider than a 700 x 28 to fit. For anything more difficult than smooth unpaved surfaces, this bike would not be suitable
https://www.dickssportinggoods.com/p...nshkmrcp15xbac

it may do ok with smooth gravel road. but i wouldn't do it if its anything more.

there are sub $1k 29er hardtail MTB that can handle rough trail a lot better

Avoid at all cost. Next thing is - you have 4-5 different discipline mountain bikes and your road bike is gathering dust in the garage. That what happened to me and my wife. First just hardtail and some simple trails, then more technical, enduro, full-blown downhill.
Started riding road again due to a back injury (mountain biking mishap... duh).