150/70 gas mileage

AK64

New Member
Joined
Jul 6, 2017
Messages
26
Reaction score
0
Points
0
Location
South Carolina
When I bought my 2012 700X, it had a 170/60 shinko street tire on the rear. I got mid to upper 60's mpg routinely. I put 705's on the bike, 150/70 on the rear and my mileage has dropped by~10 mpg. Has anyone else seen this kind of drop in mileage?
 

670cc

Super Moderator
Staff member
Super Mods
Site Supporter
Joined
Aug 7, 2012
Messages
7,784
Reaction score
778
Points
113
Location
USA
The two tires you describe have different outside diameters and will roll different revolutions per mile. Going to the 150/70 will make the speedometer and odometer read lower than actual, thus your MPG calculations will appear to have dropped. Although it will not account for the whole 10 MPG, it will account for some of the difference.

The solution is to install a speedometer correction device so you can calibrate your speedometer for different rear tire sizes or different final drive gearing. I run a 150/70 rear. I use a Speedo-DRD device, and I’m able to set it up to make the speedometer match the GPS.

Edit to add: There are tire size calculators out there so you can make a correction factor for your speedometer error. Here is one such calculator: Tire Size Calculator - Compare Tire Sizes | Tacoma World
 
Last edited:

AK64

New Member
Joined
Jul 6, 2017
Messages
26
Reaction score
0
Points
0
Location
South Carolina
Thanks 670. I had checked out the tire size calculators; it looks like there was a 0.9% difference in the diameter -- the 150/70 being larger, in diameter. Perhaps it's a combination of the diameter difference and the fact that I changed them in the Fall and did most of my riding when it's cooler. I like the 705's, so I may try the 170/60 when the 150/70 wears out, or go with the OEM size in another brand.
 
Top