Stock rims + Winter tires

[levifig]

So,

I've been researching this quite a bit and, while there's plenty of info on each tire model, there doesn't seem to be a lot on tire sizing for the stock rims… I guess people just assume everyone else knows their tire/rim sizing… :P

So my direct question is: will 205/55R17 fit on the stock rims (215/45R17 stock tires)? How will the speedometer be affected?

Feel free to link to good explanations on tire sizing. I'd love to see some tips collected here on winter tire sizing (e.g. narrower tires > wider tires, etc)

So… anyone?
Thank you.
--L

[levifig]

FWIW, I've seen plenty of recommendations for 205/50R17 on the stock rims… Just not sure how the taller tire will affect the car or if it simply won't fit!

[Suberman]

Originally Posted by levifig

So,

I've been researching this quite a bit and, while there's plenty of info on each tire model, there doesn't seem to be a lot on tire sizing for the stock rims… I guess people just assume everyone else knows their tire/rim sizing… :P

So my direct question is: will 205/55R17 fit on the stock rims (215/45R17 stock tires)? How will the speedometer be affected?

Feel free to link to good explanations on tire sizing. I'd love to see some tips collected here on winter tire sizing (e.g. narrower tires > wider tires, etc)

So… anyone?
Thank you.
--L

Yes, no problem. The stock wheel is 7x17 and a 205/50 x17 will fit just fine.

The tire isn't any taller because the tread width is narrower: 50% of 205 = 45% of 215 so sidewall height is identical. (Only 2% taller, depending on actual manufactured sizes).

Don't do it though because the 215/45x17 is already narrow enough.

I actually fit 225/45x17 winters and will fit the same size summers.

Bonus, fitting either of these alternative sizes will make your speedo more accurate!

One thing to remember : fitting taller but narrower tires of the same rolling circumference makes the ride harder because ride comfort is proportional to the air spring effect of the tire. Wider tires have more volume which lowers the effective spring rate of the tire.

You also have to increase tire pressure for taller but narrower tires to compensate for this smaller internal air volume.

[levifig]

Originally Posted by Suberman

Yes, no problem. The stock wheel is 7x17 and a 205/50 x17 will fit just fine.

The tire isn't any taller because the tread width is narrower: 50% of 205 = 45% of 215 so sidewall height is identical. (Only 2% taller, depending on actual manufactured sizes).

Don't do it though because the 215/45x17 is already narrow enough.

I actually fit 225/45x17 winters and will fit the same size summers.

Bonus, fitting either of these alternative sizes will make your speedo more accurate!

One thing to remember : fitting taller but narrower tires of the same rolling circumference makes the ride harder because ride comfort is proportional to the air spring effect of the tire. Wider tires have more volume which lowers the effective spring rate of the tire.

You also have to increase tire pressure for taller but narrower tires to compensate for this smaller internal air volume.

I was actually wondering about 205/55s… Thanks for the rest of the explanation. I think the biggest thing you said was how 215 is already narrow "enough"… I'm guessing the "enough" there has something to do with some sort of contact surface x car weight ratio.

Unfortunately, Michelin doesn't seem to make Pilot Alpin PA3 in that size…

[SamS]

This Miata site has a calculator to quickly compare sizes, but actual tire size will still vary by manufacturer.

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

[levifig]

Originally Posted by SamS

This Miata site has a calculator to quickly compare sizes, but actual tire size will still vary by manufacturer.

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

Awesome link! Thanks!

Now to find out if the stock rims can handle 205/55R17 (vs 215/45R17 stock tires)… I'd do 205/50 but TireRack doesn't have the Pirelli Sottozero in that size… Will I find them elsewhere?! Or even better, some Michelin Alpin, maybe the Primacy PA3s?

Cheers

[Suberman]

Originally Posted by levifig

I was actually wondering about 205/55s… Thanks for the rest of the explanation. I think the biggest thing you said was how 215 is already narrow "enough"… I'm guessing the "enough" there has something to do with some sort of contact surface x car weight ratio.

Unfortunately, Michelin doesn't seem to make Pilot Alpin PA3 in that size…

Narrow tread is thought to drive through deep snow more easily because the leading edge of the contact patch is narrow.

That may be true but most winter driving is not done in deep snow. Most times we are actually looking for ice traction in winter, ice or hardpack. For that narrow tires offer no advantage.