David,
I did not order any tubes either when I ordered my tires.
However, I purchased truck inner tubes which came with the bent metal valve stems in size 8.25 x 15 and they work just fine in my MRF tyres.
I don't recall the maker but one of the tubes that came with the original truck tires was a Michelin tube in that size. You might want to check with a local tire shop.
Best regards,
Jim