215/45/17 to 225/45/17?

If a guy were to swap the 215/45/17s for 225/45/17s, how much affect would the taller sidewall have on the speedometer?

It would effect it 1.4% meaning if it says 60 you are actually going 60.9mph. I have this size on my wagon for winter and so far so good.

 

http://www.miata.net/garage/tirecalc.html

Thanks. I just came across that link.

 

I was swapping my mechanical boost gauge for an electronic yesterday, and when I took the front drivers side wheel off, the inside of the tire was down to the belts. 40k miles on the original RE92s. I ended up replacing them with 225/45/17 kuhmo ecsta asx's.

Stock speed overestimates actual speed. 225/45/17 will get you closer to actual speed, prolly will still read above.

why is the sidewall taller? they are both 45/17's

why is the sidewall taller? they are both 45/17's

 

http://www.1010tires.com/TireSizeCalculator.asp ftw

Stock speed overestimates actual speed. 225/45/17 will get you closer to actual speed, prolly will still read above.

 

 

Yup, I actually found that going to a 225 make my speedometer exactly accurate, whereas it read fast with the 215s.

 

Yet more evidence Subaru should have used a decent 225 tire as OE

fascinating. Any performance benefit going to 225's or 215's?

why is the sidewall taller? they are both 45/17's

 

why is the sidewall taller? they are both 45/17's

 

The second number is a ratio of width to sidewall height, not an exact number.

 

Therefore, 215/45/17 has a sidewall height of 215 * .45 or 96.3mm. 225/45/17 has a sidewall height of 225 * .45 or 101.25mm.

fascinating. Any performance benefit going to 225's or 215's?

 

You do end up with 10mm more of contact patch and the fact that pretty much any tire is better than the stock RE92.

^ depends on the tire. not all tires of the same width are identical. look at the manufactures website and check out tread and sectional widths.

Stock speed overestimates actual speed. 225/45/17 will get you closer to actual speed, prolly will still read above.

 

 

Is there a reason *why* the stock speedo/tires over-report actual speed ?

Is there a reason *why* the stock speedo/tires over-report actual speed ?

 

So you don't get yourself into trouble. A lot of cars do that these days.

Is there a reason *why* the stock speedo/tires over-report actual speed ?

It may stem from the European (EU) requirement that prohibits vehicle speedometers from under reporting speed.

also your contact patch changes if you have a wider wheel to put them on. This squares up the shoulders.

i know squat about wheel/tires. so 225's fit out stock 17x7's? never new

yes, I've even crammed on a set of 235/45/17 on the stock wheels, but I didnt like the steering response.. some others on the forums have done so and they are fine for daily driving.

 

going from the stock 215/45 to a 225/45/17 is hardly anything worth noting for when you use it for daily driving. At this point, the only sure bet is that you have a tire that has a slightly higher load capacity, which is nice for the heavy car..

will the 225 be less effective in snow/slush over the 215? Is it gains of going from 215->225 worth any negatives?

rain and snow you want to go narrower so you can have more psi at your contact patch to cut through the snow. Unlike dry driving where you are trying to spread your weight over a large contact spot, you want to centralize it to where you can cut into the snow and rain..

so for an all season you'd probably want 215 over 225? If you were running 2sets, 225 for summer and 215 for winter?

Nah, you want 205/50/17 for winter, and depending on the tire (Nokians are narrow) 225/45/17 as well. You get some extra sidewall with either choice.

 

I regret not buying Nokians in 225/45/17 instead of 215/45/17.

 

I don't get why Xenonk is saying narrow is better in rain. Maybe in standing water, but on wet surface, wider is better.

 

Finally difference 225 vs. 215 contact patch wise is fairly small.

195 if you can find a narrow enough tire for winter use.. then I would use 245 and wider for summer

I don't get why Xenonk is saying narrow is better in rain. Maybe in standing water, but on wet surface, wider is better.

 

 

As you drive faster, you have a greater chance of hydroplaning, especially when it's a hard surface smacking up on another hard surface.. If your tires can pump out enough water, then it's fine to go wider, but the wider the tire, the more water it has to channel the water out from the center line to the edge of the tire. Also, it's a common rain setup to go as wide as you can IF your tires can handle the siping, and also lower tire pressures to soften the sidewalls to easily transition of you turning the wheel.

 

While the rain is an easier medium to move around the grooves of the road and tire, you have to look at how comfortable you are when comes to a wet surface or driving through the pouring rain.