Speedometer Changes
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Freshman User
Joined: Mar 2003
Posts: 32
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From: Wisconsin
Speedometer Changes
Howdy all,
Just wondering what, if any speedometer changes I might expect in upgrading my tires from 235/30/16 to 275/70/16.
Just bought 4 Bridgestone Dueler A/T Revo's - Very very nice tire. Smooth, quiet and handle wonderfully. A tough looking tire that gave me a little more ground clearance.
Would the difference in tire size make any significant changes in the speedometer reading?
Thanks for any and all input.
Just wondering what, if any speedometer changes I might expect in upgrading my tires from 235/30/16 to 275/70/16.
Just bought 4 Bridgestone Dueler A/T Revo's - Very very nice tire. Smooth, quiet and handle wonderfully. A tough looking tire that gave me a little more ground clearance.
Would the difference in tire size make any significant changes in the speedometer reading?
Thanks for any and all input.
Posting Guru
Joined: Dec 1999
Posts: 1,903
Likes: 2
From: Copley, OH
Speedometer Changes
Please re-type that tire size. Do you mean 235/30-16 or 235/70-16? I'm assuming you mean 235/70-16
235/70-16 tires roll at about 718 revs per mile.
Your new tires roll at 668 revs per mile.
So your speedo will read low. At an indicated 65, you'll actually be going 70. The difference will also affect your anti-lock brake system and if you have an automatic, it will affect tranny operation.
235/70-16 tires roll at about 718 revs per mile.
Your new tires roll at 668 revs per mile.
So your speedo will read low. At an indicated 65, you'll actually be going 70. The difference will also affect your anti-lock brake system and if you have an automatic, it will affect tranny operation.
Thread Starter
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Freshman User
Joined: Mar 2003
Posts: 32
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From: Wisconsin
Speedometer Changes
Just to clarify....The tires that I have on now are 265/75/16's (I actually went out and looked at the tires this time....) I think I even screwed that up in the origional post.
So, the new tires are taller and wider than the last set.
So, the new tires are taller and wider than the last set.
Senior User
Joined: Jun 2003
Posts: 434
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From: Hawaii
Speedometer Changes
What size are the new ones? If they are 275/70r16 then they are actually smaller in diameter than the 265/75r16's. Approx 31.8" for the 265/75 and 31.2" for the 275/70's. Look at the sticker on your driver's side door jamb and see what size the ORIGINAL tires were on the truck. The speedometer was originally set for those tires at the factory.
Last edited by CPerry; Sep 9, 2003 at 05:17 PM.
Junior User
Joined: Feb 2003
Posts: 58
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From: PA, USA #1
Speedometer Changes
The difference will also affect your anti-lock brake system and if you have an automatic, it will affect tranny operation. [/B][/QUOTE]
I went from 265 75 r16 to 315 75 r16's and I notice that if I need to break hard the pedal goes to the floor is this what you mean by affecting the ALS???? also how will it affect the tranny????
I went from 265 75 r16 to 315 75 r16's and I notice that if I need to break hard the pedal goes to the floor is this what you mean by affecting the ALS???? also how will it affect the tranny????
Posting Guru
Joined: Jul 2002
Posts: 2,205
Likes: 1
From: Vancouver WA
Speedometer Changes
The transmission will shift at the wrong times because it will think you're going a different speed than you actually are.
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Thread Starter
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Freshman User
Joined: Mar 2003
Posts: 32
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From: Wisconsin
Speedometer Changes
To truly clarify......
My old tires were: 235/30/R16 (OEM size tires)
My new tires are: 265/75/R16
I have found a site that figures out your tire dimentions and speedometer changes by plugging in your factory tire size and the replacement tire size. It works for both U.S. designation tires and for metric TRX designation tires.
Try it:
http://www.csgnetwork.com/tireinfo4calc.html
The Circumference of my new tires is 9 inches more than my OEM tires. This means that when my speedometer shows 65mph I'm really only going about 59mph.
I have noticed that it does take more braking to stop my truck now with the bigger tires. It also seems to take more gas to drive at highway speeds.
My new tires are 2 1/2 inches taller and 1 1/2 inch wider than the OEM. Can anyone say if that will cause any significant transmission problems (automatic)? Are there trany upgrades that can be done to compensate? I havn't noticed a difference in shift points.....
Mike
My old tires were: 235/30/R16 (OEM size tires)
My new tires are: 265/75/R16
I have found a site that figures out your tire dimentions and speedometer changes by plugging in your factory tire size and the replacement tire size. It works for both U.S. designation tires and for metric TRX designation tires.
Try it:
http://www.csgnetwork.com/tireinfo4calc.html
The Circumference of my new tires is 9 inches more than my OEM tires. This means that when my speedometer shows 65mph I'm really only going about 59mph.
I have noticed that it does take more braking to stop my truck now with the bigger tires. It also seems to take more gas to drive at highway speeds.
My new tires are 2 1/2 inches taller and 1 1/2 inch wider than the OEM. Can anyone say if that will cause any significant transmission problems (automatic)? Are there trany upgrades that can be done to compensate? I havn't noticed a difference in shift points.....
Mike
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