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Old 07-24-2008, 03:47 PM   #85 (permalink)
Z man
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Join Date: May 2008
Location: WV
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xBox - '05 Scion xB
90 day: 40.85 mpg (US)
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Originally Posted by xbUser View Post
If I change the tire from 185-60-15 to 185-65-15, same width, but taller. The ratio would be 1:1.023. Before 3000rpm@60mph, 3250rpm@65mph. After change: 2930rpm@60mph, 3175rpm@65mph. 3000rpm@61.42mph. If VVTi changes timing @3100rpm, then I can drive @63.47mph rather than 62mph with better efficiency after the change. Am I right? Too bad, doesn't make much difference.
Yeah the low geared transmission does hurt.

My problem is constantly trying to coax the auto to stay in 4th gear where the rpms drop significantly.

I just checked, 40mph is 1,800 rpms in overdrive, what is it in 5th gear?
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