Hi, recently I changed my road bike brakes for a Shimano tiagra one. The rear brake worked well, but the front caliper is not large enough to reach the rim and it touches also in the wheel. I adjusted the pad for the last position but wont work.
Does anyone know if there is a kind of front brake with calipers bigger than those of shimano tiagra? I dont feel like buy a new fork
See a photo below of the brake.

It's not about not being "large" enough, it's about not having enough "reach". Determine the "reach" of your current brake, then go looking for one with more "reach".

If only one shoe comes up short (high) then the brake isn't symmetrical and you need to readjust the small centering screw on top (if there is one) so both arms line up evenly on top.

Otherwise the brake is simply too short. Depending on how much room you need you have a few options. It appears pretty close in the photo, so here are some options which can be used singly or in combination.

1- buy a longer brake
2- shave the tops of the shoes at an angle so they don't overhang the rim. Use a swiss rasp, coarse file, or coarse sandpaper wrapped around a paint stirrer.
3- file the bottom of the slots on the brakes so the shoes can go a bit lower (2mm max is safe, more isn't)
4- file the tops of the dropouts so the wheel sits higher, 2mm is fine, but you have to do this right
5- file the mounting holes in the fork (front and back) so you can lower the brake. This won't work if the brake uses a recessed nut in back.

Good luck

Looks like you need long reach calipers as #dabac notes, like Shimano R650 or Tektro R539 (plenty of others available) would be useful to know what you had on originally, the tire looks to be a 32mm? larger than a 'road' bike would normally take, also, you may want to put an end cap on the cable, as it looks as though it is starting to frey already.

Your Tiagra caliper is rated at 39-49 mm reach.

A Shimano A550 brake is rated at 47-57 mm. It's roughly the same price.
Tektro offers a number of dual pivot brakes with 47-57 mm.

FWIW, reach is the vertical distance from the brake mounting hole to your rim's brakeing surface.

Graphically, this:


Source: Sutherland's 6th Edition

As shown above reach is to the center of the shoes. So if you're measuring brake hole to rim, you also need to measure from center of the hole to the center of the brake track.

not that i would do it, but as an alternative you could file the fork dropouts a bit or the caliper brake slots. i've heard that there are brake pads that have an offset attachment bolt that may be of help too.