Biggest rear tire

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Hello I'm try to find the the biggest tires for my 79 El Camino can some plz help hopefully I'm trying to get at least 10 in without any changes stock suspension

 

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Generally 275/60's are the largest tire that fit a G-body in back without frame/fender mods, or jacking the car into the sky. In front, 255 or wider requires some inner fender mods and/or larger diameter wheels to clear the suspension components. 245's should fit in front with the right backspacing (larger diameter wheels may be needed) without major inner fender mods.