tire question need help

[kx100master]

Hi,
I have a carter bros kart with 145/70-6 tires I need an equivalent street tire or turf tire since the offroad one wears out super fast. Thanks

 

[KartFab]

you can go up a size to the 15" turf tires. They sell them at walmart and are like 1/2" bigger

 

[kx100master]

does the width matter?