iron duck
The Wheel Spacer was left off the MLG. I assume the job of the Spacer is to insure Space between wheels. Also space between
Tyres, and tyre and bits. If allowed to rub, Rubber casings can ignite into an impressive display within moments. The Tyres may have been afire before the burst, liberating already burning torch bits to then ignite the Fuel, post-burst. Burt Rutan's Space Rocket Fuel? Rubber. Not kidding. Are we sure it was not the Spacer that started the Fire/Burst, or Burst/Fire?
merely a 'post-existing' theory
da bear