@DTR+NSR I was unsure how old the tubes were which came with my bike, so I took the opportunity to fit new tubes for peace of mind, along with the new TrailRiders. I bought these heavy duty ones from ebay for £12 each, as they looked good quality ;
http://www.ebay.co.uk/itm/YAMAHA-DT125R-DT-125-FRONT-REAR-TYRES-TUBES-RIM-TAPES-PUNCTURE-SEALANT-U-CHOOSE-/282081065568?var=&hash=item41ad577a60