Verification: 265/65 vs. 265/70

[GreyhoundGuy]

EDIT/UPDATE: I bought Firestone Destination A/Ts this morning ... 265/70/17 and had them mounted on the 17x7.5" FJ rims that I picked up on Friday night. The ride is fantastic. I think it's the best call I could have made!

Thanks for all the advice and suggestions!

-Joel

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I've got a friend that just bought a '13 Tacoma in July. She doesn't like the tires (BFG Rugged Terrains, 265/65/17) and wants to buy quieter highway tires. I told her I may be interested in buying them, and I'm sure she'd cut me a great deal. (Her tires are basically new. She's hardly driven the Taco.)

The 65 is the part I'm worried about. I checked some sites (including this one), and it shows that my speedo could be off by a couple mph... 55 mph shown would be 53.24 mph, 70 mph shown would be 67.76 mph. I'm not overly concerned about the speedo issue... more about the difference in shown mileage and actual mileage.

This site shows that the 245/60/20s that my LE is running now has a circumference of 99.2 inches. The 265/70/17s has a circumference of 99.29... REALLY close to the factory setup. The 265/65/17s have a circumference of 96.02 inches... a difference of 3.28 inches. Three inches seems minor... but the 265 takes 21 extra revolutions per mile... for about 63 inches per mile. Over the course of 50,000 miles, that's 3,150,000 inches, or 262,500 feet, or 49.71 miles. (I think I'm doing that math right.)

My thoughts are that the 265/65 is A) going to show me the wrong speed, B) give me the wrong mileage, and C) give me the wrong info for mpg... so it's a no brainer to buy the 265/70s.

What say y'all? Go with the 265/70s and stay really close to the original circumference, or go with the 265/65s and deal with the issues... but potentially save a good chunk of money?

-Joel

 

[AZrunner11]

With the way you put that- hypothetically if I purchase a vehicle running 285s then the odometer is pretty much way off?? I glazed over during math portion-

 

[GreyhoundGuy]

With the way you put that- hypothetically if I purchase a vehicle running 285s then the odometer is pretty much way off??

Probably not. The part I was concerned with was the second number, the ratio/percentage.

And yes, the math confused me, too. But I love numbers, so figuring out that kind of stuff is fun.

-Joel

 

[Canazes9]

I didn't verify the math, but its definitely close if not spot on. Differences in mileage/revolutions/speedometer error are minor and not really much of a reason to be concerned w/ the tires. The tires being undersized will look a little odd on your 4Runner. An even bigger reason not to get them is that they are sucky tires (my Tacoma came w/ them also).

I'm also a little confused on how you plan to fit these 17" tires on your 20" rims or is there a rim purchase in their that I missed?

David

 

[adam2562]

if u want more ground clearance, get the 70... i vote for 70

 

[BobsTrail]

Tire Size Comparison
Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
265/65-17 6.8in 15.3in 30.6in 96.0in 660 0.0%
265/70-17 7.3in 15.8in 31.6in 99.3in 638 3.4%

 

[Viper45]

Tire Size Comparison
Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
265/65-17 6.8in 15.3in 30.6in 96.0in 660 0.0%
265/70-17 7.3in 15.8in 31.6in 99.3in 638 3.4%

Actually, the rev/mile you show here is incorrect. The 265/70R17 = 657 revs/mile (+/-1 depending on the manufacturer)

1010 Tire Calc and confirmed with TireRack's data cache/Manufacturer data from both OEM tires available in this size.

Don't worry, I made the same mistake in my hand calcs (2nd part of that post), and still don't understand why...

 

[kowski49]

ound:

I'm also a little confused on how you plan to fit these 17" tires on your 20" rims or is there a rim purchase in their that I missed?

David

Yeah, I think he got some 17" FJ rims

 

[Newf4R]

Speedo will be off, only slightly but still off.
Tires are smaller which will look worse IMO.
Rugged Terrains are not a great tire... Again, just my opinion.
Original Manufacturer tires will wear faster than normal.

I like a deal like the next guy, but I think you will regret this one in the long run. I like many others here ditched the original tires for an upgrade, not a downgrade which is what this sounds like to me.