It's getting near time to replace my 17'ers and was thinking of going wider. Which size is more correct, 215/45 or 215/40? I think one of them is supposed to help correct the speedometer inaccuracy.

Also, for those that have these sizes, any opinions as to drawbacks or benefits of either size. I would think that turn-in might be slightly effected, but might be outweighed by the additional grip.

 

Hello Davis,

I recently replaced my runflats with 215/40/R17 Conti Extreme DW. The 40 series is slightly smaller in diameter and as you stated, the 215 gives a wider contact patch. I really happy with this set-up. I'm lowered on KW 2's and no problems with rubbing. From what I've read, the smaller diameter works well, gearing wise with our cars. My speedo reads about 2-3mph faster than actual as veryified by my GPS. I'm also effectively running ET35 offset, ET 40 wheel and 5mm spacer. Let me know if you need a pic of that set-up, hope this helps.

 

I Think He Only Was Asking About Tires Not Rims And And Offsets and What Not, But Yes 21540 Is Closer To The Stock Diameter Tires

 

go with the 215/45 and you will be closer to OE . see this tire calculator ---
http://www.miata.net/garage/tirecalc.html

 

I went 215/40 and they are more comfortable of a ride than 205/45 runflats.

 

I believe what you meant to say is you are traveling 2 to 3 MPH slower then your speedo says?

http://www.discounttiredirect.com/di...foTireMath.jsp
here is a link to another tire size calculator


I have run at least 4 different sizes on my car, so far the best one is a 215 45 17, if I decide to go with a 40 series i would do a 235 40 17, but not many tires in that size. Good luck to you

 

I had 215/40 when I got my car. But after 2 bent wheels from pot-holes I went with 215/45's. No more bent wheels.
Your damage may very.

 

That is what I meant to say, thanks Fixed my original post

 

215/45/17 is no prob. I was running Hankook Ventus V12 Evos slammed on Bilstein Coilovers and I had no rubbing issues whatsoever. Was very happy with the ride quality.

 

Any pics of the 215/45's?

 

Hrmmm don't have any closeups, but here are some old pictures of the 215/45/17 Hankook V12s






The rims I had were 40 offset, so anything between 40 and 48 offset I'm sure would be fine.

If you are lowered, I would want to watch out with 35 or lower offset with 215/45/17 tire.

 

With the Bilstein PSS9s I would go with 15s or 16s. Those 17s lowered kinda look like 19s.

 

Hey stranger!

I've been running 215/45's for 70,000 miles.



This size made my speedo almost perfect.

I'm about to order new summer wheels and leaning toward 16" for lower weight and more rim protection with a bit higher profile tire on a light wheel. Might even look better with the amount I'm lowered.

 

My first tires after leaving the runflats behind were 215x40. They felt wonderful, but the low profile made for problems with potholes (and Dallas has pretty good streets). I bubbled the sidewalls on 2 tires.

If you do get the 40 profile, buy the extended tire warranty.

I buy 45 profile now unless it is for track only.

 

If I was going to go with a 40 versus a 45 in my area - I think I would just ding all the rims with a 5lb sledge hammer first to pre-disaster them - that way I won't feel so bad later when the potholes do their thing!!! A 45 has marginal cushion IMO for protection of the rims for my area.

DAn

 

If you thought those lowered Konigs look like 19s...

Then my 17" OZ rims REALLY look like 19s when lowered lol.

 

OK, thanks guys. Decided to stick with the stock 17" size for now. Just ordered a set of Continental ExtremeContact DW's from Alex at the Tire Rack.

 

215/45/17 non-runflat. Never had a problem and they ride nice. WAY nicer than the OEM runflats. Ack!

 

Hey Paul! Are you going to the Dragon this year??