Carburetor size Question

CRUZE 418 said

I have 255/60/15's on my Dart with 3:55's, rpm at 55mph is 2500. If you are driving that far, I would go 3:23, maybe 2:76, but that's just me. It doesn't sound to me like you want drag strip fast. She's gonna go through gas if you run her hard.

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With 3.23’s and a 255 tire it would be 2270 rpm @ 55 mph. A 275 tire would be 2189 rpm @ 55 mph.

A 3.55 rear and 275’s would be 2400 rpm @ 55 mph. As you stated, 3.55’s and a 255 would be 2500 @ 55 mph.

The MPG choice would be a 2.76:1 with the 275 tire putting it at 1870 rpm @ 55 mph.

Leaning toward a 275/60-15 with 3.23’s.