Tire size to make speedo more accurate..??

[David]

Looking to replace my stock 225/50-16 tires. With the stock size my speedo is running about 2-1/2% high. The stock tires have a diameter of 24.86" so to get the speedo to read right I need a tire with a diameter of ~25.48".
235/50-16 = 25.25"
225/55-16 = 25.74"
Any advice on if one or both of these sizes will fit without rubbing or clearance issue?

1994 LSi

Thanks.

[Green1995SVX]

Are you actually serious?

[Crazy_pilot]

Check into the manufacturers specs for tire diameter, they can vary quite a bit from one to the other, even in the same size.

And yes, those will fit just fine, although 235 is quite wide for stock wheels.

[David]

Yep, I'm serious. Having my speedometer off is a pet peeve. Think Subaru even was sued over this.

[benebob]

No speedometer is closer than a couple percentage points. Remember it reads based on the diameter of the tire (which of course changes with every mile driven)and is set up for the diameter of the stock tire brand (the diameter does change by manufacturer and style quite a bit without changing the advertised tire size). The reality is that manufactures' have been sued for it but not for reading to high but rather reading too low, that's why all manufactures read a couple percentage lower these days. A while back I saw a study that showed the European manufacturers were about 5 percent more optimistic, the domestics 3 percent and Japanese 2 percent on average.

[David]

I thought Subaru was sued because your mileage warranty would expire before you had "really" travelled the distance.
Googled and found this:
http://www.topclassactions.com/open/...action-lawsuit

[benebob]

And there is an idiot born everyday keeping our elected offices full.

[LetItSnow]

Now, now... Let's not dispute whether this is in any way sensible - that's not the question.

As Chris said, the 235s are a little wide on the stock wheels.

For clarity: The class action lawsuit applied to 2002-2007 vehicles, due to an alleged 8% odometer error - a measurement not necessarily tied 1:1 to the speedometer. As industry standard is more accepting of 2.5%, you will probably find yourself agitated by a hell of a lot of cars.

[David]

For what it's worth my '07 Honda Pilot's speedometer/odometer is dead on with the stock size tires.

[XT6Wagon]

Be interesting to test out the error. I know the error was tested out for the 04 STi and it turned out to be an offset + small error. Forgot the exact numbers but it was something like actual 60mph, shown 65mph. But at 120 actual mph it would show 126mph. Steep slope from 0-30 real speed to about 4 mph off at 30 (ie shows 34). Then the actual calibration error kicks in for the slight difference in slope of the offset.

That said, I love that my F150 reads dead on at highway speeds. Just pop the cruise for actual speedlimit and never have to worry about an honest cop (not found in Beaverton, OR and other locations).

[92snowmachine]

unless your speedometer says "certified mileage" under it you will probably be slightly off. the scanner at work shows cars mileage in the computer which rarely to never matches the odometer reading shown on mechanical gauges. only exception is police vehicles and taxis that have the mileage certified. there is probably a company locally that can do this for you if you are that concerned.