Same as always: All three tuning forks are close together in the same lab in an inertial frame, etc. You see the same ratios as the lab does. If you compare

Same as always: All three tuning forks are close together in the same lab in an inertial frame, etc. You see the same ratios as the lab does. If you compare with some tuning forks on your space ship, then just use special relativity to compare the ticks on your space ship versus the ones in the lab. If the tuning forks are 'standard', say, some spectral lines, the you can see your time dialation.