My speedometer is off by a ratio of .94

[GeoffM]

The reason I think its off:
I can set my cruise control at 80 and use gps tracking on my phone. 75.5 mph.
I can really get a decent read at slower speeds though. I did just change my tires and the tire size. We're supposed to have 60's, there were 65's on it and I put 60's back on it. If, at the next tire change I replace them with 65's will my speedometer go back to normal?

Also, now that I can post in the not beginner section should I be posting these there?

[MrSpeedy]

The reason I think its off:
I can set my cruise control at 80 and use gps tracking on my phone. 75.5 mph.
I can really get a decent read at slower speeds though. I did just change my tires and the tire size. We're supposed to have 60's, there were 65's on it and I put 60's back on it. If, at the next tire change I replace them with 65's will my speedometer go back to normal?

Also, now that I can post in the not beginner section should I be posting these there?

It's normal that your speedometer is a bit off after changing the tires smaller or larger. It does that with every car cause the rotation the tire does is faster/slower on different size of tires. But if you change same size tires,then you shouldn't see the difference on speedometer. So don't worry, everything is ok with the speedometer. Not sure if you get the point from my explanation.

And for the section part, i don't know. Been wondering it myself. Though, if I have a really "dumb" question or small issue then I post it on the beginner section cause I believe there are more people who can answer to my question. But if it's really a pain in the ass and haven't found answer anywhere else then I post it on the members section. Also if its something that might break something expensive (like engine) then I usually ask help from the members section. Of course you can still break something, but that's just me.

[visualpoet]

Mr. Speedy is right about tires and speedometer changes.


As for posting, you're not forced to leave the beginner section, you just get the privilege of posting with the big kids now!

[djcaz_aom]

Here is a helpful link. Just plug in your OE size and then your current size.

Tire Calculator

185/70 R14 for DX and LX

195/60 R15 for EX and SE

[GeoffM]

MrSpeedy: I get what you're saying, but I had not stock size and now I do. Now my speedo is off. But I didn't think to gps test the not stock size. So, as far as I know I either need to: Switch back to not stock size (65's) or find the speed gear in the trans and change it(not going to happen)

visualpoet: I think I'll follow MrSpeedy's method of posting

djcaz_aom: I have the 10th, so that translates to R15's. That chart seems to confirm my suspicions. That the tires that came with the car (65's) are actually the right size and the correct size as identified by my door label(60), is actually the wrong size.

Either way, I've got some time to think about it. The tires have an 85k tread life.

[Fleetw00d]

There is no speed gear in the transmission. There is an electronic vehicle speed sensor (VSS) that sends a pulsing electrical signal that drives the speedometer and odometer. The 195 represents the width of the tire in millimeters. The 60 or 65 indicates the height of the sidewall as a percent of the width. So for a given width, the higher the aspect ratio, the taller the tire, the faster the actual speed for a given transmission output speed (indicated speed). Keep in mind that worn tires are smaller around than new ones as well. Haven't messed with the instrument cluster or VSS have you?

[GeoffM]

I haven't gone near any of it. Wiring is something I'd like to stay away from as long as possible. Not having to crack open my trans to replace gears sounds a lot better though. As long as its only off at highway speeds, I think I can deal. How hard is it to replace? And in some cars I've driven the odometer was driven by the speedometer. So, is the fictional 4.5 mph being added to my odometer?

[Fleetw00d]

That would be a good test for the highway. In my wagon, the speedo was off when I replaced the cluster printer circuit board (had to use a sedan board, they are different), but the odometer was correct. I fixed my wagon by installing a sedan speedo. Check the odometer against your GPS or highway mile markers. If the odo matches the speedo, it is probably your tires. If the odo is correct, then maybe a new speedo is needed.

[92exa6]

I've never owned a vehicle that read actual road speed. It's illegal for the MFGs to sell a car/truck/motorcycle that has a speedometer that reads low, so they tend to error between 2 and 5% on the high side. Many magazine reviews will show a 30 and 60mph indicated/actual result. Often you'll see 57-58 actual mph at an indicated 60. A four mph difference at 80 seems reasonable. If you were going 80 and the speedo read 75, then I'd worry.

[Fleetw00d]

My 90, 93 wagon and 93 sedan all read within 1 mph of the GPS speed. 93 EX actual speed is about 2 mph low at 60. 99 E350 actual speed is about 1 mph high at 60. A 4 mph error would drive me crazy (I'm an engineer).

[wed3k]

hate to say it but mine was about 5mph off. old car, i dealt with it.

[GeoffM]

So, the ultimate question. Ahould I replacwe the vss? I read on other postes it can go asd vchecp as %20. ALort cheaper than cracken ppen the trans and teplacing a gera. 4.5 mph os botheren me. But idf its acceptable I wil deal.

[wed3k]

i think i replaced mine and it stayed the same.

[islandhopper]

So, the ultimate question. Ahould I replacwe the vss? I read on other postes it can go asd vchecp as %20. ALort cheaper than cracken ppen the trans and teplacing a gera. 4.5 mph os botheren me. But idf its acceptable I wil deal.

What?

[GeoffM]

So, the ultimate question. Ahould I replacwe the vss? I read on other postes it can go asd vchecp as %20. ALort cheaper than cracken ppen the trans and teplacing a gera. 4.5 mph os botheren me. But idf its acceptable I wil deal.

So, the ultimate question. Should I replace the vss? I read on other posts it can go as checp as $20. Alot cheaper than cracikng open the trans and replacing a gear. 4.5 mph is bothering me. But idk if its acceptable I will deal.

I really want to go for a bike ride. More then anything.