How much will 285s throw off speedo/odo

ashby · 09-22-2009, 01:39 AM

My stock size tire is 245/75-16 and now I have 285/70-17 I was wondering how much these will throw off the odometer and speedometer?

__________________
-00 Dodge Ram 2500-
-6spd-Dana 80-3:55 Gears-
5" TBE-BHAF-H2 wheels and 285s.

dodge17 · 09-22-2009, 02:17 AM

When your speedo is reading 60 you will actually be going 65. It would be off roughly 7.5%

__________________
1998 Dodge Ram 2500 4x4 12V Club Cab Long Bed Hopeful Mod List: TC/VB, S&B Intake, 4in Exhaust, #10 Plate, Triple Gauge Pod

ashby · 09-22-2009, 11:01 AM

Ok, but will this affect the odometer readings any?

__________________
-00 Dodge Ram 2500-
-6spd-Dana 80-3:55 Gears-
5" TBE-BHAF-H2 wheels and 285s.

ah64id · 09-22-2009, 11:37 AM

Quote:

Originally Posted by ashby

Ok, but will this affect the odometer readings any?

Yes, its directly tied to the speedo.

Without knowing the exact tire mfgr this is just a guess, but OEM was 682 rev/mile and 285/70/17 is 636. So a difference of 46 rev/mil or 6.7%.

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05 3500 QC LB NV5600 4X4 SRW
Pricol's (EGT, Boost, DP, FP, Oil)
Amsoiled, BMK-11
GDP MK-2+ w/ Cat 2 mic
Smarty Jr Revo

**SOUTHERN SMOKE** · 09-22-2009, 11:44 AM

this is weird, mine read the same when i put 285's on my truck, and i used gps to measure it....

edit: nevermind saw your stockers where a 16... yea it will be off about 5mph give or take 1

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ah64id · 09-22-2009, 11:53 AM

Quote:

Originally Posted by SOUTHERN SMOKE

this is weird, mine read the same when i put 285's on my truck, and i used gps to measure it....

edit: nevermind saw your stockers where a 16... yea it will be off about 5mph give or take 1

16's have nothing to do with it. You can get a 285/75/16 and still be off the same.

And there is not set mph they are off, its a percentage so the difference gets larger at higher speeds.

__________________

05 3500 QC LB NV5600 4X4 SRW
Pricol's (EGT, Boost, DP, FP, Oil)
Amsoiled, BMK-11
GDP MK-2+ w/ Cat 2 mic
Smarty Jr Revo

09-22-2009, 01:39 AM	#1 (permalink)
ashby Cummins Enthusiast Join Date: Mar 2009 Location: Tennessee Posts: 207 Thanks: 1 Thanked 6 Times in 5 Posts ashby's Truck Pics	How much will 285s throw off speedo/odo My stock size tire is 245/75-16 and now I have 285/70-17 I was wondering how much these will throw off the odometer and speedometer? __________________ -00 Dodge Ram 2500- -6spd-Dana 80-3:55 Gears- 5" TBE-BHAF-H2 wheels and 285s.

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09-22-2009, 02:17 AM	#2 (permalink)
dodge17 Cummins Fanatic Join Date: Nov 2008 Location: Maryland Posts: 193 Thanks: 0 Thanked 5 Times in 5 Posts dodge17's Truck Pics	When your speedo is reading 60 you will actually be going 65. It would be off roughly 7.5% __________________ 1998 Dodge Ram 2500 4x4 12V Club Cab Long Bed Hopeful Mod List: TC/VB, S&B Intake, 4in Exhaust, #10 Plate, Triple Gauge Pod

09-22-2009, 11:01 AM	#3 (permalink)
ashby Cummins Enthusiast Join Date: Mar 2009 Location: Tennessee Posts: 207 Thanks: 1 Thanked 6 Times in 5 Posts ashby's Truck Pics	Ok, but will this affect the odometer readings any? __________________ -00 Dodge Ram 2500- -6spd-Dana 80-3:55 Gears- 5" TBE-BHAF-H2 wheels and 285s.