Wheel diameter vs rpm

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BlueMeanies

Member
Joined
Mar 22, 2014
Posts
94
Reaction score
6
Location
Fayetteville, AR
Ram Year
2007 QCSB RWD
Engine
Hemi 5.7
Now that I've been driving the truck for a while, the new power/torque curve of the 260 cam is starting to grow on me.

The cam starts to kick in at 2300~ish. By 3500 the truck pulls really hard. By 4500 it's freakin' rockin'! I'm still wanting for a bit more bottom end grunt though-fer pulling trailers, city MPG, quickness, 'n such.

Rather than doing gears (running 3.92 now) I'm pondering going smaller in wheel diameter. The truck currently has 275/60/20. 33” dia. The options are a 275/45/20 (29.75”) or 285/50/20 (31”).

Perhaps this is a stupid question to ask and not phrased very well but here goes. What might this do to city and hwy RPM's? I don't want to completely suck gas at ludicrous hwy rpm/mpg. Towing vs unloaded?
 
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