I was also going to post a link to Adaptivemall.com, but several people beat me (a good thing).
One nice thing I have heard about them, is that they are very helpful on the phone with sizing info, etc. There is a link near the bottom of the page for sizing help. Some of the strollers on that site won't work for him because they might only go up to 110 pounds or the seat width is fairly small (15.5 inches).
This chair is an example from that site of the "transport chair" like Cheshire Figment mentioned. Here's another
site with transport chairs. If you do an internet search for "transport chair" or "Companion chair", you will find all sorts.
Most of the transport chairs don't recline (they are sort of "plain vanilla" versions just to get someone from place to place). If you need reclining,
this site is the home site for Convaid (one of the strollers that someone provided a link to). On their site, you can see what other choices they have available for larger kids and you could email some questions regarding the features you need.
You also want to check if your insurance will cover (if you have a 15 yr old in need of a stroller, they
should cover it. The insurance company may cover at a higher rate if you use their "preferred provider" than if you just go anywhere for it. You would need a prescription and a "letter of medical necessity" if insurance will be involved. If your child already works with an OT or PT, they can help. If he doesn't, your school should have OT or PT as a resource. They may say that a stroller doesn't "fit" into school services, but if they would ever use it for field trips, it would.
