On my steam roller, I used Andrew Price’s rust node layout for the wheels and roller. I can’t figure out why the texture is OK on the wheels, but out of focus on the roller.
Great model.
Most likely:
You’re not using the uv space efficiently. If the roller is a separate object and there are no other textures on it, you could go into the uv editor, select the roller verts/uvs and scale them up, this will make the texture appear smaller, thus increasing the effective resolution.
The alternate to that is in the nodes, right before the image texture node(s) add a texture coordinates and a mapping map. Wire the uv into the mapping, and then increase all 3 scales, then wire the vector into the image texture and the texture will appear smaller with a higher resolution.
You appear to have a seam right in the front of of the roller. Behind it would be a better choice, you could just rotate it around.
There’s a final possibility that the image texture you are using is just too low of resolution. Judging from your screenshot I would hazard to guess that the minimum size for your rust texture should be 2048 x 2048 pixels.
Really nice deatailing and great model.
If you haven’t looked into image based lighting (ibl), and hdri’s this model is pretty much made for them.