Large tires & slow speed

awhile back with one of the online "garage sales" i picked up some tires that turned out to be 7" and weigh over a pound each, but they were so cheap i had to get some of them

so... if i install these tires on a rc8t or a converted 3.3 revo and gear for 20-30 am i still asking for trouble.

with the rc8t i can gear for around 23mph as lowest

with the revo 3.3 i can also gear for around 23 as well

i do want the low speed and huge tires but i also would like to keep my drive train and diffs intact

i have 3s 4s 5s for power and 10t, 13 ,15 ,18 tooth pinions so i have options


any suggestions or previous experience would be helpful