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#21
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#22
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Quote:
Importsmasher
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Scott Baggiore 66 GTO convertible 389/4 speed (parents bought new) 73 Firebird Formula 400/4 speed 74 GTO 455/4 speed 74 Grand Am |
#23
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Quote:
Importsmasher
__________________
Scott Baggiore 66 GTO convertible 389/4 speed (parents bought new) 73 Firebird Formula 400/4 speed 74 GTO 455/4 speed 74 Grand Am |
#24
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Current Pontiacs - 1973 Formula SD455 - #'s auto orig paint 1972 Trans Am - 4 speed orig paint 1974 Formula 400 - Ram Air automatic 1966 2+2 convertible - 421 4bbl automatic 1967 Grand Prix - 4 speed orig paint 1967 GTO - 4 speed orig paint 35k orig miles |
#25
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Quote:
Original tires would have been GR70-15 w/o space saver spare.
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So long, farewell. |
#26
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I have 245s in the front and 275s in the back of my 71, and everything clears and handles great.
My 77 has 225/70s on all 4 corners, and that also rides great and cleats everything.
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"Those poor souls have made the fatal mistake of surrounding us. Now we can fire in any direction" 1970 Trans Am RAIII 4 speed 1971 Trans Am 5.3 LM7 1977 Trans Am W72 Y82 1987 Grand National |
#27
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There was Y99 before Radials... fyi..
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"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather |
#28
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Correct. In '73, the F60-15 was the other 15" option, at a different cost.
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So long, farewell. |
The Following User Says Thank You to Held for Ransom For This Useful Post: | ||
#29
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interesting.
This thread made me look it up - for 1973 the Y99 did NOT require Rally II or Honeycomb wheels - that is a new revelation to me!! But back to the question at hand. F70-14 or GR70-15 would have been the (non-radial) tires used on a Formula Firebird; For 1970-1972 the standard and optional tires were F70-14 or F60-15. My understanding to this point is that although the letter sizing used on bias ply tires was in essence supposed to convert across, but it less than perfect; This is my understanding of cross reference from old to new tires (taking more into account the diameter once installed and aspect ratio): F70-14 = 225 70 14* F60-15 = 235 60 15 GR70-15 = 225 70 15 * = Some sources cite a 215/70/14, but if you dig further, it's a bit too short. I believe that all these sizes when mounted on 7" wide wheels, were roughly the same overall diameter. E78-14 (blackwall) was the n/c tire for base and Esprit; Optional on the base or Esprit was E78-14 whitewall, F78-14 (blackwall or whitewall), and F70-14 (blackwall or whitewall). The E78-14 tire was mounted on a 6" wide wheel. The F78-14 & F70-14 were mounted on a 7" wide wheel. The n/c tire for the Formula was F70-14 (blackwall); Optional on the Formula was F70-14 whitewall, or GR70-15. All of the Formula tire sizes were mounted on a 7" wide wheel. The tire predicated the wheel - not the other way around, and this is why there is virtually no mention of wheel width.
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1970 Formula 400 Carousel Red paint on Black standard interior A no-engine, no-transmission, no-wheel option car. Quite likely one of few '70 Muncie three speed Formula 400's left. 1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing) 2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs) |
#30
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Quote:
Thanks everyone for the input! Good information, and I learned a lot! Importsmasher
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Scott Baggiore 66 GTO convertible 389/4 speed (parents bought new) 73 Firebird Formula 400/4 speed 74 GTO 455/4 speed 74 Grand Am |
#31
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Here is the info on 1973 Formula's and tires.
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So long, farewell. |
#32
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Wheel / hub cap / wheel cover Choices brought about some of the confusion, But Customers started this asking for wheels/ tires that were NOT available on the model they want. There are a bunch of 15" tire cars in 71, 2 and 3 that did Not have Y99. I owned a 71Esprit 400 with 15 Honeycomb wheels and white line tires.. Anything to sell a car..
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"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather |
The Following User Says Thank You to Formulabruce For This Useful Post: | ||
#33
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Thought I'd follow up on this thread. I found a set of dog dishes on ebay, and bought a new set of 15x7 steel wheels from Summit. Got them painted body color (Admiralty Blue) and mounted a set of 225/70-15s on them. I know some people don't care for the dog dish look, but I love it. And my son is happy cause he got my old Honeycombs for his 69 Firebird.
Thanks for all the input! Importsmasher
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Scott Baggiore 66 GTO convertible 389/4 speed (parents bought new) 73 Firebird Formula 400/4 speed 74 GTO 455/4 speed 74 Grand Am |
The Following 2 Users Say Thank You to importsmasher For This Useful Post: | ||
#34
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My Formula originally had GR-70x15 radial tire option on steel wheels and moon caps.. I am currently running 245/60R15's on 15x7 Rally II's.
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Current Pontiacs - 1973 Formula SD455 - #'s auto orig paint 1972 Trans Am - 4 speed orig paint 1974 Formula 400 - Ram Air automatic 1966 2+2 convertible - 421 4bbl automatic 1967 Grand Prix - 4 speed orig paint 1967 GTO - 4 speed orig paint 35k orig miles Last edited by 71GP76TA; 12-26-2023 at 12:38 PM. |
#35
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Although the sizing doesn't convert across, I like the following:
Bias Ply "F" tread width = 235(mm) radial tread width Unfortunately to get the proper portions of contact width and diameter you have move things around so that they are not generally accepted tire conversion sizes. Bias ply tires (at least to me) have a better look because of a flatter side wall and wider contact width; while radial tires have a more rounded sidewall and with a smaller contact width. On 7" wide Rally II wheels, I like a 235/60R14 in place of an F70-14, and a 245/60R15 in place of either a F60-15 or GR70-15. 245/60R14 are too wide for a 14x7 Rally II, and 255/60R15 are too wide for a 15x7 Rally II - both wear from the center out... I have learned this from personal experience. But they both looked great!
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1970 Formula 400 Carousel Red paint on Black standard interior A no-engine, no-transmission, no-wheel option car. Quite likely one of few '70 Muncie three speed Formula 400's left. 1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing) 2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs) |
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