So if you increase the size of your vehicle tires...

[ARCHIVED THREAD] - So if you increase the size of your vehicle tires... (Page 1 of 2)

Posted: 12/3/2016 8:53:10 AM EDT

and don't alter your speedometer it will be off right?

So does that mean you are reall going faster or slower than it says. For example, I'm traveling 60mph but had bigger tires put on my truck. Will me speedometer say I'm going faster or slower than 60?

Posted: 12/3/2016 8:54:52 AM EDT

[#1]

Just like gears...

The taller tire or gear, the slower you will show on your speedo.

Posted: 12/3/2016 8:55:07 AM EDT

[#2]

Your speedometer will read slower.

what size are you going from and what are you wanting to put on.

Posted: 12/3/2016 8:55:23 AM EDT

[#3]

Bigger tires will show a slower speed than what you're actually doing.

Posted: 12/3/2016 8:55:27 AM EDT

[#4]

its so minimal but if you want to know approximately what it will be:

calculator

Posted: 12/3/2016 8:55:34 AM EDT

[#5]

well smaller tires would rotate faster, so....

Posted: 12/3/2016 8:55:40 AM EDT

[#6]

Slower

Posted: 12/3/2016 8:57:08 AM EDT

[#7]

Quoted:
and don't alter your speedometer it will be off right?

So does that mean you are reall going faster or slower than it says. For example, I'm traveling 60mph but had bigger tires put on my truck. Will me speedometer say I'm going faster or slower than 60?

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you are going slower than what the speedometer says. by how much, not sure. when i was younger, i had a 85' toyota 4x4 with 40" gumbo's on it and speedometer showed 45 and was actually going 55.

Posted: 12/3/2016 8:57:11 AM EDT

[#8]

Programmers can correct it on modern vehicles.

Confirm with gps for fine tuning.

Posted: 12/3/2016 9:00:51 AM EDT

[#9]

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Quoted:
Your speedometer will read slower.

what size are you going from and what are you wanting to put on.

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academic discussion with a co-worker. I did go from 31s to 35s on my jeep a few year ago though. Don't think I ever had it fixed.

Posted: 12/3/2016 9:01:18 AM EDT

[#10]

This is why you change your axle gearing along with your tires (among other reasons)

Or you could just use a GPS.

Posted: 12/3/2016 9:02:44 AM EDT

[#11]

what if you put the truck on a treadmill?

Posted: 12/3/2016 9:06:56 AM EDT

[#12]

I went from 265 to 315 tires when I purchased aftermarket wheels.

I read about 5 mph low at 70mph according to Waze and my speedo.

Posted: 12/3/2016 9:08:35 AM EDT

[#13]

FPNI

Posted: 12/3/2016 9:11:21 AM EDT

[#14]

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Quoted:
what if you put the truck on a treadmill?

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The truck will not be able to take off.

Posted: 12/3/2016 9:15:42 AM EDT

[#15]

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Quoted:
I went from 265 to 315 tires when I purchased aftermarket wheels.

I read about 5 mph low at 70mph according to Waze and my speedo.

View Quote

This just means wider. Aspect ratio determines height.

Posted: 12/3/2016 9:18:06 AM EDT

[#16]

Why would you need to make a poll long after your question was answered?

Posted: 12/3/2016 9:25:48 AM EDT

[#17]

BMW are always slower by 2 mph even on oem tires.

Posted: 12/3/2016 9:30:31 AM EDT

[#18]

Slower.

You can figure the circumference of both tires and the percentage difference and that should give you the change.

Posted: 12/3/2016 9:31:47 AM EDT

[#19]

When I was growing up this type of question could be answered by any 7th grader based on public school basic education.

Now in public schools the teachers AND students can't even figure out which shitter to use.

Posted: 12/3/2016 9:45:44 AM EDT

[#20]

It's ? based.
Example . At 60, you're really doing 66. At 80, you're really doing 88. Etc

Posted: 12/3/2016 9:46:24 AM EDT

[#21]

Slower.

Posted: 12/3/2016 9:47:10 AM EDT

[#22]

Quote History

Quoted:
When I was growing up this type of question could be answered by any 7th grader based on public school basic education.

Now in public schools the teachers AND students can't even figure out which shitter to use.

View Quote

16% of arfcom can't figure it out either according to the poll.

Posted: 12/3/2016 9:51:25 AM EDT

[#23]

Dealer or someone with a flash can re-program and correct speedo. Google or check a Jeep forum.....they do it all the time.

Posted: 12/3/2016 10:32:27 AM EDT

[#24]

Don't forget to adjust your headlights after putting bigger tires or a lift/level kit on either.

Posted: 12/3/2016 10:38:00 AM EDT

[#25]

Quote History

Quoted:

academic discussion with a co-worker. I did go from 31s to 35s on my jeep a few year ago though. Don't think I ever had it fixed.

View Quote

And you didn't re-gear it at the same time

Posted: 12/3/2016 10:45:26 AM EDT

[#26]

Quote History

Quoted:

This just means wider. Aspect ratio determines height.

View Quote

Aspect ratio x width determine height, so wider is taller too if the aspect ratio remains the same.
A 265x70x16 is 30.6 tall, a 315x70x16 is 33.4 tall.

Posted: 12/3/2016 10:48:16 AM EDT

[#27]

Quote History

Quoted:

This just means wider. Aspect ratio determines height.

View Quote

This

Posted: 12/3/2016 10:49:55 AM EDT

[#28]

Quote History

Quoted:

Aspect ratio x width determine height, so wider is taller too if the aspect ratio remains the same.
A 265x70x16 is 30.6 tall, a 315x70x16 is 33.4 tall.

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People who understand how it works don't do that.

Posted: 12/3/2016 10:50:41 AM EDT

[#29]

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Quoted:

This

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Look right above your post, I explained it. You can double check on most tire manufactures websites as they typically list installed height.

Posted: 12/3/2016 10:51:18 AM EDT

[#30]

Right after I got married, my wife and I borrowed my fil's truck to go to Chicago.

Speed limit was like 60 & according to the speedometer I was going 65 - my standard 5 over when on highways.

The whole way there & back I was blasting past other drivers like they were standing still. In fact, it became a joke during the trip - that apparently Illinois people drive like little old ladies on the highway.

Well, after we get back I find out that the fil had oversized tires on the truck & that it usually ran about 8 or so mph faster than the speedo read.

So, in reality, I was blasting through Illinois going about 13 over the speed limit the whole way. Which kind of explains why I was passing everyone.

Posted: 12/3/2016 11:20:36 AM EDT

[#31]

It will show slower. I don't readjust the speedometer. I figure out the difference between stock and new tire size in percentage. Apply that and you know what's what.

Posted: 12/3/2016 11:27:11 AM EDT

[#32]

Quote History

Quoted:
well smaller tires would rotate faster, so....

View Quote

Umm, no.

A.W.D.

Posted: 12/3/2016 11:29:39 AM EDT

[#33]

Larger tires have a larger circumference, ie: you cover more ground per revolution than you do with a smaller tire.
Speedo is reading revolutions, and is calibrated to translate to MPH based on circumference of tire.

A.W.D.

Posted: 12/3/2016 11:37:17 AM EDT

[#34]

https://www.tacomaworld.com/tirecalc

Quote History

Quoted:
Don't forget to adjust your headlights after putting bigger tires or a lift/level kit on either.

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Ditto.

Posted: 12/3/2016 11:46:25 AM EDT

[#35]

slower, but generally still within the margin of error for most radar guns and police

Posted: 12/3/2016 11:53:44 AM EDT

[#36]

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Quoted:
slower, but generally still within the margin of error for most radar guns and police

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Depends on the tire size difference. Going from the stock 32s on a Jeep Rubicon to 37s will have a considerable effect.

Posted: 12/3/2016 12:01:47 PM EDT

[#37]

Before tire change: Put needle at 60, you're going 60
After change to bigger tires: Put needle at 60, you're going faster than 60

Posted: 12/3/2016 12:04:44 PM EDT

[#38]

You will be going slower than indicated.

For example on my Toyota FJ, when the speedo says 70 mph, I am actually going 65 mph.
I have an android app called DigiHUD that uses gps to calculate speed, so I can check.

Posted: 12/3/2016 12:05:12 PM EDT

[#39]

Quote History

Quoted:

And you didn't re-gear it at the same time

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Quoted:

Quoted:

academic discussion with a co-worker. I did go from 31s to 35s on my jeep a few year ago though. Don't think I ever had it fixed.

And you didn't re-gear it at the same time

I went from 265/75R16 to 315/75R16 and didn't re-gear - no ill effects, in fact drive ability improved.

Posted: 12/3/2016 12:07:45 PM EDT

[#40]

Your indicated speed will be slower than your actual speed.

Posted: 12/3/2016 12:08:12 PM EDT

[#41]

Quote History

Quoted:
You will be going slower than indicated.

For example on my Toyota FJ, when the speedo says 70 mph, I am actually going 65 mph.
I have an android app called DigiHUD that uses gps to calculate speed, so I can check.

View Quote

You probably need to check it again, what your describing defies physical laws. Larger tires cover longer distance with each rev, that means you'll be going faster than the speedo indicates.

Posted: 12/3/2016 12:16:48 PM EDT

[#42]

Quote History

Quoted:
Just like gears...

The taller tire or gear, the slower you will show on your speedo.

View Quote

Not always with gears, depends where the speed sensor is. If the sensor pickup is wheel speed instead of driveshaft speed (such as a tone ring on the ring gear), changing gears doesn't affect the speedo.

Posted: 12/3/2016 12:16:52 PM EDT

[#43]

When I put 35" tires on my Jeep my speedo would read lower than actual speed. Easy fix with aev procal, was also able to adjust tpms for lower tire pressures.

Posted: 12/3/2016 12:17:35 PM EDT

[#44]

Quote History

Quoted:
You will be going slower than indicated.

For example on my Toyota FJ, when the speedo says 70 mph, I am actually going 65 mph.
I have an android app called DigiHUD that uses gps to calculate speed, so I can check.

View Quote

Your speedo read fast to begin with - larger tires brought it closer to actual ground speed.

My '02 Honda VFR800 motorcycle speedo was ~10% fast from the factory.

Posted: 12/3/2016 12:18:47 PM EDT

[#45]

Quote History

Quoted:

You probably need to check it again, what your describing defies physical laws. Larger tires cover longer distance with each rev, that means you'll be going faster than the speedo indicates.

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
You will be going slower than indicated.

For example on my Toyota FJ, when the speedo says 70 mph, I am actually going 65 mph.
I have an android app called DigiHUD that uses gps to calculate speed, so I can check.

You probably need to check it again, what your describing defies physical laws. Larger tires cover longer distance with each rev, that means you'll be going faster than the speedo indicates.

Don't assume the speedo was accurate to begin with.

Posted: 12/3/2016 12:20:16 PM EDT

[#46]

Quote History

Quoted:

Not always with gears, depends where the speed sensor is. If the sensor pickup is wheel speed instead of driveshaft speed (such as a tone ring on the ring gear), changing gears doesn't affect the speedo.

View Quote View All Quotes

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Quote History

Quoted:

Quoted:
Just like gears...

The taller tire or gear, the slower you will show on your speedo.

Not always with gears, depends where the speed sensor is. If the sensor pickup is wheel speed instead of driveshaft speed (such as a tone ring on the ring gear), changing gears doesn't affect the speedo.

You need to re-think or re-explain.

Posted: 12/3/2016 12:20:44 PM EDT

[#47]

It means you are going faster than indicated...ask the cop who pulls you over how fast you were going.

Posted: 12/3/2016 12:26:01 PM EDT

[#48]

Quote History

Quoted:

You need to re-think or re-explain.

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
Just like gears...

The taller tire or gear, the slower you will show on your speedo.

Not always with gears, depends where the speed sensor is. If the sensor pickup is wheel speed instead of driveshaft speed (such as a tone ring on the ring gear), changing gears doesn't affect the speedo.

You need to re-think or re-explain.

Don't know how else to explain it. If your speed sensor picks up from the ring gear, your speedo isn't thrown off when you swap from say 3.55s to 4.56s. Driveshaft/pinion speed sure changes, but the ring gear is still turning the same speed at a given vehicle speed, assuming of course tire size has not changed.