I found 4 275/50/14 bf goodrich tires today (new) $300 Will these fit my 14 stock 1970 chevelle rims and car?(rear) they measured 8" inside and 11.5 " tread Thanks, Dave

They might be unused but are certainly not new! BFG has not made a size like that in 10 or 20 years! Those tires would not be safe to run on your car and are too wide for a 7" wheel anyway.