Tire sizing

My '05 Hatch has the stock wheels back on for now, until I get new tires. Problem is, the stockers are 185/60R14, but we have a bunch of those "Your Speed" signs and I am consistently running 3MPH under my indicated. I check at 50MPH, they say I am going 47MPH. So am I going to have to go smaller in diameter to even this out? I don't want to go too much smaller, my Konig 16's are harsh enough as it is. Maybe a different speedo gear from a 15" Aveo?

[xstevex]

a lot of times they make the speedo in the car faster than what you really are going to save you money in tickets.... thats what ive heard atleast, how true it is i dont know.

but many speedos get off the faster you go, my old car was off i know that. I havent checked the aveo though.

[Fighting Irish]

Yeah, car manufacturers are not allowed by law to have speedos that read lower than the true speed. Therefore, to be on the safe side, they post a higher speed than it actually is. Usually its no more than a couple percent.

They had an article about it either in Car and Driver or Motor Trend back about 5 years ago. They even tested each manufacturer to see whose speedometers were the most accurate. If I can remember correctly, Chevy was probably in the upper third for speedometer accuracy.

[xstevex]

Usually its no more than a couple percent.

And the faster you go the more of a difference that small percentage is.

I thought it over, I would have to go a bit larger to even things out.

Thanks for the replies.

[Kinkyllama]

I thought it over, I would have to go a bit larger to even things out.

Thanks for the replies.

The sidewall number, probably 50 or 45 for your car is the % of the width. So a 215/45/16 is going to have a slightly taller sidewall than a 205/45/16. There are calc. you can find online that'll tell you how much of a difference it'll make in both your speedo or size.

Also stretching a smaller tire on a bigger wheel than it's ment for makes it a bit smaller, learned that the hard way... my car barley makes it over most speedbumps, got a 13mm wider wheel and 10mm skinnyier tire and couldn't make it over most speedbumps cuz it lowered the car nearly 1/4"

[aveodude]

Also stretching a smaller tire on a bigger wheel than it's ment for makes it a bit smaller, learned that the hard way... my car barley makes it over most speedbumps, got a 13mm wider wheel and 10mm skinnyier tire and couldn't make it over most speedbumps cuz it lowered the car nearly 1/4"

Not to mention stretching a tires is horribly unsafe because during minimal lateral movement (i.e. interstate offramp/onramp) it can cause the tire to pop off the bead. That is a Euro fad that needs to go away.

[mikedudley17]

i thought i read somewhere the aveo speedo is off by 7%. dont remember where i saw this tho...

[mikedudley17]

i love how much you are helping the forum!!! thanks!!!

i love ur bicycle tires

[Kinkyllama]

Not to mention stretching a tires is horribly unsafe because during minimal lateral movement (i.e. interstate offramp/onramp) it can cause the tire to pop off the bead. That is a Euro fad that needs to go away.

lol they aren't stretched like that, only a little bit. Just noticable. Improves hanlding, mostly turn in. It's a 205mm tire on a 7.5" wheel, I've seen the same sized tire on 9" wide wheels many times.