Speedometer reading incorrect speed after replacing rims/tires to bigger size

DENO2970

MEMBER
1995 TOYOTA CAMRY
3.0L
6 CYL
2WD
AUTOMATIC
190,000 MILES

Speedometer 9 miles above speed reading. I did switch the tires from 15" oem tires and rim to 16" aluminium rims and tires.
I have also been having intermittent problems with setting the cruise control.
Speed sensor?
Capacitors ((3)) on speedometer gauge?

4 Replies

JACOBANDNICKOLAS

MECHANIC
109,747 POSTS

Hi,

Going to a bigger tire will slow the revolution of the tires. That would make it read slower than you are going. Just for curiosity, what size tires were on the vehicle, and what was installed? I'm asking so I can calculate the rotations per mile. Even though you went to a 16", if the profile is low enough, it could spin faster.

Let me know.

Joe

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Thursday, July 8th, 2021 AT 8:33 PM

SQM

MECHANIC
6,383 POSTS

Hello,

First of all can you tell me the tire size that was on your OEM wheel and the tire size on the 16" wheel?
Depending on the options Toyota used either 205/60/15 or 195/65/15 as OEM for that year.
You might find this link helpful:

The correct size for the 16" wheel should be 195/55/16 or 205/50/16 size tires.

Here is the tire size understanding guide:

https://youtu.be/HDQ40hjWrRM

Let me know what you have.

Thanks.

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Thursday, July 8th, 2021 AT 8:40 PM

DENO2970

MEMBER
19 POSTS

205/60 R 15 OEM factory aluminum rims which came on the le sedans.
Switched to a 205/60 R16 Aluminum from tirerack which is on the car now.
Oh FYI, here's what I have also noticed in diagnosing the inaccuracy in speed, as the vehicle increases speed, the deviation increases. For example, at 20MPH true, speedometer reads 23, at 40MPH it reads 45. At 60 MPH it reads 68.

Also the cruise control acts up now and then. Sometimes it won't set initially then goes into fault (blinks 5 times then shuts down) code. The ignition key must be turned to off position in order to reset the cruise.
The only reason I bring this up is that the speed sensor seems suspect.
Do you think it could be causing both problems? Speed reading incorrect and the cruise control issues?

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Friday, July 9th, 2021 AT 4:49 PM

JACOBANDNICKOLAS

MECHANIC
109,747 POSTS

Hi,

Absolutely a speed sensor can be causing all the issues you are experiencing. If there is a fault, the speed could be wrong, the CC may not work, and oftentimes (if equipped) the ABS, traction control, and stability control can fail.

I calculated the tire size difference. Here are my calculations:

205 60 15 = 817 revolutions per mile

205 60 16 = 786 revolutions per mile

Based on that, the speedo should be working the opposite of what you are experiencing.

The VSS can be the issue, but it's odd that it happened with the tire change and in the opposite manner I would have thought. What I suggest is to have the computer scanned for diagnostic trouble codes.

I have a list of codes that are related to the VSS. However, I don't want to send you on a wild goose chase. If you can, have the computer scanned to see what is indicated, if anything. Here is a video showing how it's done:

https://youtu.be/YV3TRZwer8k

Most parts stores will do that for you. If you can, see if there is something stored. If there isn't we will start with one diagnostic at a time.

Let me know.

Joe

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Friday, July 9th, 2021 AT 9:08 PM