Treadmill for heavy people

I'm a single mom of an young adult on the severe end of the autism spectrum. He has some weight to lose and so do I. What is the best treadmill for heavy people? I'm looking to buy one for the home. He elopes runs away so I can't take him in public much.

I'm 280 ish and he is 315. I found some with a 300 limit. I can use starting off and once we get him below 300 he can use it too. I've made food changes but since we can't get out much I'm looking to purchase something we can use at home. I have a recumbent bike and looking to add a treadmill.

Any treadmill with high weight limits?