Tire and rim Trouble

:banghead: Ok i have a 1994 ford explorer sport my rims are 15 inches and my tires are P235/75R15 im looking at new rims and tires for it but im confused because some tires say 35/12.50R15 or like that but thats nothing like what mine say and i dont want to get tires that would not fit. Also i do not know how to match up tires with rims to make sure they fit. If there is anybody who can help me with this problem i would greatly appreciate it. Again in case your confused i am wondering how to buy rims and tires that will fit on the rims. Thank you.

Paul