I don't know that bike, but you should be able to go to 25mm and maybe higher. Look and measure around the brake bridge on the rear of the frame and where the rear tire comes closest to the seat tube and chain stays and see what kind of clearance you have. On the front check around where the tire passes through the fork for any issues.

It is general guideline that a tire's maximum width be no more than double the interior rim width (inside the hooks). For many road rims that is 13-14mm which would suggest a 28mm max on the tires.

And for reference, I weigh 180lbs and typically ran 23mm tires at 100f/110r. I could go down to 90/100psi without pinch flats with a 25mm tire. I have since switched to using 23mm tires on wider rims which also allows me to run at 90/100.

Note that rim specs often list the rims exterior width, but not always interior. If that is what you have, subtracting 5-6mm should get you close to the interior. So the common 19-20mm ext will have an interior of 13-14. The 'new' 23mm rims that are popular usually have an interior width of 17-18, and that is also similar of many touring and sport rims that have been around for a long time.

Also, you are really asking about 'tires/tyres', not wheel size.