Rented a 4x4 hilux, now questions about tires

Rented it for a safari tour. After roughly 2 weeks of use they look like this:http://ift.tt/2tJQKDs front tires. Rear tire look normal. Is the damage inflicted by us? If yes how? Or are these cheap/old tires or normal use?Brand is Mudstar.Thank you in advance via /r/cars http://ift.tt/2sM3A74