175/65R14 VS. 175/70R14

[Stustu07]

Hi guys, my name is Stuart. So I'm no stranger to forums, I did some searching and didn't come up with anything that directly answered my questions. I'm asking these questions on behalf of my girlfriend. So she has a 2007 manual 4-door Hatch (Canadian Car), that currently has 175/65R14's on the car. I wanted to know how much of a change would there be on the speedo if she changed to 175/70R14's. She's staying with a 14" steely as these are for winter driving (better in snow compared to 15's), and she wants a nicer ride feel. I know 14's ride nicer than 15's comfort wise (depends the person and other suspension components). The reason I'm asking is because I have really no idea how changing tire sizes effects the Yaris.. I know on my car I have 2 speedo gears, one on the trans and one on the actual speedo; changing tire sizes if not done correctly would cause me to have to change 1 of the 2 gears to get the right reading on the speedo. All help/info is appreciated, thanks!

(Btw I use this site when comparing tire size changes tire size comparing site)

[SirDigby]

well....it's an 8.75 mm difference, larger. so....around 2 Kmph faster than displayed speed at 80Kmph (1.5 Mph at 60 Mph)

[Stustu07]

Alright thanks, I was just trying to figure out how much of a difference it would make on her to mileage count, was hoping it would only make a small change like the site I use says.. Just didn't know if the speedo was flexible on it's readings, meaning I didn't know how precise the speedo reading is with stock tire size.. Have seen here and there that some people have gotten better readings changing tire size, that's why I wanted to know how much of a change in reading would occur. Thanks.

[kevinj93]

There is a 3% difference in diameter. You cqn compare the speedometer reading to a GPS to see if there is a difference worth worrying about.

[thebarber]

When the speedo says 100kph you're actually going 103

But if it's anything like my echo hatch, the speedo reads high in the first place

[kimona]

The speedo is probably not accurate out of the box.

BTW, 185/70/14's are the same diameter as OEM 185/60/15's.

[Stustu07]

Alright thanks guys! I'll be testing accuracy with my GPS on Wednesday in her car. Also wasn't OEM in Canada 175/65R14 on the base models? So I'm guessing the speedo's in the 14" and 15" cars are the same (RS vs Base vs LE)?

[thebarber]

Originally Posted by kimona

The speedo is probably not accurate out of the box.

BTW, 185/70/14's are the same diameter as OEM 185/60/15's.

OEM for 2007 was 175-65-14 in Canada

[kimona]

Originally Posted by thebarber

OEM for 2007 was 175-65-14 in Canada

Thanks. Yes, I am aware of that. The OP seemed to be concerned that 175/70/14's may be too tall for his car, so I wanted to assure him that they would work since OEM 185/60/15's are the same diameter.

[IllusionX]

I run 195/60R15 in the winter, and I really enjoy the 1/2" extra ground clearance I get.

Sent from my SM-G930W8 using Tapatalk

[SirDigby]

Originally Posted by Stustu07

Alright thanks guys! I'll be testing accuracy with my GPS on Wednesday in her car.

I wouldn't trust a gps. sometimes my gps says i'm moving 3 mph when i'm sitting at a red light...

[NYC-SE]

Originally Posted by SirDigby

I wouldn't trust a gps. sometimes my gps says i'm moving 3 mph when i'm sitting at a red light...

Buy a new GPS.

[SirDigby]

why would I buy a new one? I don't have it to tell me how fast i'm moving, that's not its function...

[dogsridewith]

By measurement w/ a thin steel tape before inflation, confirmed by actual tire specs provided by TireTrack site, these 175/70R14 Yokohama IceGuard IG52C studless winter tires are 4.3 % taller than the baseline 175/65R14 given by the Tacoma tire link in Post 1. Shown on OEM 5" wide steel rims w/ Tercel centercaps and short valves. Tread width measures 6" between sharp cornered shoulders. Beads were visibly close before installation. Installer asked if I knew these were going to be this tall.
Smooth and quiet and seemingly free-rolling on pavement. Car drove and steered nicely on one slushy snow section of high-crown gravel road w/ a moderate hill (up and down.)

[CrankyOldMan]

The other consideration is the visible accuracy of the speedo: parallax from different driver positions will slightly alter the location of the needle over the tick marks, easily causing a few percent error. Oh, and you should be more focused on looking out the windows than your speedo.

[dogsridewith]

Do we know for sure that Toyota didn't somehow setup speedometers differently for the nominally 3.4% different height tires they were installing?

[Yaris709]

My speedo on my 07 Sedan was slower with the 175/65r14's. I run 185/70r14 in winter and 195/60r15 summer and those are within 1km/h from speedo to gps

[kimona]

After replacing the OEM 185/60/15's (23.7" dia.) with 205/50/16's (24.1" dia.), my speedo was dead on!