by HK1837 on Thu, 20 Jul 2017 8:19 +0000
As far as I am aware changing away from original tyre diameter to larger will normally have adverse affect on a diesel's economy. But so will pushing it as at the end of the day 3L in a 2tonne vehicle is working hard to push the car through the air.
As a comparison my 2011 SR5 V6 auto averages 14's over 100000km. can hit 15's if towing a laden car float and sitting on the 100kmh speed limit for 5+ hours. On a drive to Melbourne and back (to Lake Macquarie) in January it did 10's and the average dropped back to low 14's. Only mods until recently other than the normal steel bar, canopy and aux battery were 2.75" extractors back exhaust and 265/65/17 tyres plus TRD front brakes.
Now it is supercharged it uses a little more around town (more to do with my right foot than anything else), but on the highway it is really frugal as it ticks along at 100 or 110 in cruise control and never drops out of 4th or 5th, just lopes along below 2000rpm.