What size are the speakers in a 2020 peterbilt 579

Try swapping out a different radio first. It is a lot easier than screw balling around with speakers

 

Cobrawastaken (or was it MIStaken....nyuk, nyuk)
I am driving a 2018 579, door speakers are 4" x 6", I just replaced them on Sunday with Pioneer TS-A462F 3-ways. The sound has improved but the Pete stock head is, like most stock stereo heads, NOT GREAT. Not that you asked, but in my opinion, the door speakers are too low compared to the level of your ears so there is too much road/truck noise. I BT with my phone but the BT connection with the head seems to "break" partially sometimes. The sound is really good and then sounds paper-bag-woofer-like after a while. It may be phone related but the Pete-radio display will say "Check Antenna" sometimes while I am blue toothing. I'd say based on my limited experience, if you want bass, a sub is probably necessary and a different head would definitely help.

Lazer--Do you have a 579 and have replaced the head?