Maximum training heart rate

I currently run twice every week and have done for 15 years. I use a chest strap to monitor my heart rate and I'm aware that my maximum training heart rate is 220-(my age) 38 = 182.
My height is 188cm, Weight 82kg.

However, with this in mind I find that I can easily achieve this maximum heart rate on a treadmill running machine after 15 to 20 minutes at 10.5km/hr with a 1% gradient. I could run for much longer although I fear I am doing myself more harm than good by reaching and exceeding my "maximum training heart rate". I've asked other runners who say I should leave the chest strap and listen to my body. If it doesn't hurt.....carry on. I have never suffered from any chest pains or breathing difficulty and I would just like some advice?

I love running and feel that I would like to continue. My goal of training to run 10km at least once per week is being prevented by current measured heart rate which I believe is too high? I have slowed the running pace by a couple of km/hr however eventually my heart rate will still peak at 100%, just at a later time.

I have also been a regular at circuit training which is a very intense training session usually about an hours duration. I have never worn my chest strap whilst in circuits however I do believe i've most definitely exceeded my 182 beats/min maximum.

I probably have many many questions, however my heart rate issue is something I need to know more about.

Regards,
Neil