195 65 r15 vs 195 60 R15

mquinnan · 07-10-2007, 01:26 PM

I am ready to put on new tires (06 prius). I Want Goodyear TT's. What is the difference between the tires mentioned above? Why do most posts recommend the 60's over the 65's? The 65's are taller........but wouldn't they actually give me less rotations per mile thereby cheating my odometer just a smidge? With the 60's I believe I would be cheated in the odometer just a bit, if i understand the sizes correctly.

usbseawolf2000 · 07-10-2007, 02:54 PM

185/65 R15 is what comes with Prius. 195/60 R15 has almost the same rotation per mile.

FL_Prius_Driver · 07-10-2007, 11:18 PM

There is a change in the aspect ratio, so there would be an effect on MPG. However, this change may be in the same error range as the MPG calculations of the Prius. Note that the rolling resistance may be different and this may have a bigger effect on the MPG then expected, so get a good MPG baseline before the change.

The tire you are selecting is a very long lasting tire if I understand right (Assurance TripleTred-Wear 740?). I think this is a good decision. Let us know how it turns out.

Bill Merchant · 07-11-2007, 01:36 AM

185/65R15 = 24.5" Outside Diameter Integrity OEM tire = 76.969" circumference = 823.188 rev/mile
195/65R15 = 25.0" Outside Diameter Assurance Triple Tread = 78.540" C = 806.725 rev/mile
195/60R15 = 24.2" Outside Diameter Assurance Triple Tread = 76.027" C = 833.393 rev/mile
(OD figures from Goodyear web site, C and rev/mile calculated, actual rev/mile different)
So the 195/65 will make your speedo and nav 2% fast (823.188/806.725) and the 195/60 will be 2% slow (823.188/833.393).

07-10-2007, 01:26 PM	#1
mquinnan Join Date: Jul 2007 Posts: 1 My Car: Model: Package: Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	I am ready to put on new tires (06 prius). I Want Goodyear TT's. What is the difference between the tires mentioned above? Why do most posts recommend the 60's over the 65's? The 65's are taller........but wouldn't they actually give me less rotations per mile thereby cheating my odometer just a smidge? With the 60's I believe I would be cheated in the odometer just a bit, if i understand the sizes correctly.

07-10-2007, 02:54 PM	#2
usbseawolf2000 HSD PhD Join Date: Sep 2004 Location: Queens, NY Posts: 3,254 My Car: 2006 Prius Model: Package: #3 Thanks: 106 Thanked 178 Times in 111 Posts Friends: 59	185/65 R15 is what comes with Prius. 195/60 R15 has almost the same rotation per mile.

07-10-2007, 11:18 PM	#3
FL_Prius_Driver Senior Member Join Date: Jun 2007 Location: Tampa Bay Posts: 1,845 My Car: 2001 Prius Model: Package: N/A Thanks: 4 Thanked 17 Times in 16 Posts Friends: 2	There is a change in the aspect ratio, so there would be an effect on MPG. However, this change may be in the same error range as the MPG calculations of the Prius. Note that the rolling resistance may be different and this may have a bigger effect on the MPG then expected, so get a good MPG baseline before the change. The tire you are selecting is a very long lasting tire if I understand right (Assurance TripleTred-Wear 740?). I think this is a good decision. Let us know how it turns out.

07-11-2007, 01:36 AM	#4
Bill Merchant absit invidia Join Date: May 2005 Location: USA \| Oregon \| Portland area \| 97004 \| Posts: 4,100 My Car: 2007 Prius Model: Package: #5 Thanks: 18 Thanked 10 Times in 8 Posts Friends: 60	185/65R15 = 24.5" Outside Diameter Integrity OEM tire = 76.969" circumference = 823.188 rev/mile 195/65R15 = 25.0" Outside Diameter Assurance Triple Tread = 78.540" C = 806.725 rev/mile 195/60R15 = 24.2" Outside Diameter Assurance Triple Tread = 76.027" C = 833.393 rev/mile (OD figures from Goodyear web site, C and rev/mile calculated, actual rev/mile different) So the 195/65 will make your speedo and nav 2% fast (823.188/806.725) and the 195/60 will be 2% slow (823.188/833.393).