Gas MIleage?

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Dec 31, 2004 | 12:47 AM

#31

gtex

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Joined: Apr 2001

Posts: 6,175

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From: Texas

Quote:

Originally Posted by biz4two

Thanks gtex...that link is a great source of info. I am actually running 32" tires with stock (Truetrac limited slip) 3.50's. I think I am still in my power band with my 390FE, but I am not sure what the original size tire was. I asked my father (purchased truck new) and he was not sure what the size would equal in inches. Maybe 28" or 29"???

I can say with certainty that the truck pulls strong even in 4th and does not seem to notice the increased tire size. Slight pressure on the gas pedal is all she needs. The secondary (4 bbls) are almost never used unless I just feel like opening them up.

Makes sense. 32s and 36s are very different animals. Original tires were probably about 30-31" tall (235-75r15s were popular). F250s+ had different size rims, but I bet the rubber was close in diameter. 3.50s with taller tires is getting out of most engine power-bands. but, like you noted, the FE 390 comes on early in the powerband. So, you don't notice much. On the other hand, get you some more appropriate 4.10s, and hold on to your shorts :-)