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View Full Version : 205/40 or 215/40


TheWanderer
06-10-2007, 09:27 PM
So I've decided to go with the Kumho MXs for mah 17x7 superlegs.

Now the question is of size...

205/40 will get me approx. .8" lower than stock but may not handle as well as 215/40s. They are also cheaper.

215/40s will probably handle better than the 205/40s while getting me about .3" lower than stock. But they are about $15 more per tire (iirc).

205/40s don't seem to be incredibly popular and I was wondering the reason. Lack of sidewall perhaps?

Anyway, what ever shall I do?

glnr13
06-10-2007, 09:38 PM
215s dont necessarily handle better than 205s. sidewall stiffness and compound of tire as well as suspension will control you're actual handling. if the sidewall is soft and you have a ballooning 215 over a 7" rim you may decrease responsiveness in turning.

TheWanderer
06-10-2007, 10:06 PM
So 205/40s it is. I was leaning this way anyway. I'll just make sure they are properly inflated.

Thanks.

Adam
06-11-2007, 02:24 AM
Remeber if you're going for asthetics, you maybe .8" lower but that means you'll also have .8" more wheel gap.

That can't be right though, I think you mean .4" lower and .4" more wheel gap?:confused:

Anywho, if it were me I'd go 215/40 or just stick with the stock 205/45.

TheWanderer
06-11-2007, 03:16 AM
I'm not going purely asthetic. I'd like to perform well also. I don't think 205/40s will perform weaker than the stock size. And I did some research over at NAM regarding what Alex from The Tire Rack said about 215/40. Doesn't seem optimal. If I was on a 7.5" rim I think I'd be in better shape with 215 but alas I a not.

Wheel gap shouldn't increase by .8". Not sure what it will go to to be honest. I plan on taking a bunch of pics during the process using measuring tape as a guide. Plan to take stock measurements (ground to fender lip, wheel gap, wheel/tire diameter). Then with the new wheels and tires on. The with the M7 springs fitted.

Hopefully will be informative. Definately will be fun. :tu:

TheWanderer
06-11-2007, 03:25 AM
Just reread amg's post. To clarify:

Using http://www.miata.net/garage/tirecalc.html it shows that the tire/wheel combo for a 205/40/17 will be 23.5". The stockers measure 24.3" in diameter.

So, the car is going to sit lower due to the fact that the diameters aren't the same. I do feel like I'm overlooking something though. Wheel gap shouldn't change that much I don't think.

Oh well, we shall see.

KiLO
06-11-2007, 05:32 AM
I am running 215/40's on my 17x7's. I like the slightly wider look, and didn't notice a difference really between these and my last tires which were 205/40. For most, you can't go wrong either way really.

RFIbanez
06-11-2007, 06:28 AM
I use 205/40-17"s and they seem pretty wide for the MX.

Another thing to consider, is the 215 heavier then the 205 series?

For a 7" wheel I'd go with 205, for 7.5" I'd go with 215.

ScottinBend
06-11-2007, 02:32 PM
The difference as posted above is slight. I am running 215 on my 7" wheels and there is no "ballooning". I like a bit more sidewall and a fuller look in the wheel well.

iDiaz
06-11-2007, 03:13 PM
What offset on those Superleggeras? 37 or 42?

You may run into some rubbing issues with 215 width on 37 offset.

glnr13
06-11-2007, 03:22 PM
pls note, when i mentioned ballooning, not all 215's balloon over the rim, depends on the rim and the tire. i.e. 215 toyos on my webspokes ballooned.

Adam
06-11-2007, 03:29 PM
Just reread amg's post. To clarify:

Using http://www.miata.net/garage/tirecalc.html it shows that the tire/wheel combo for a 205/40/17 will be 23.5". The stockers measure 24.3" in diameter.

So, the car is going to sit lower due to the fact that the diameters aren't the same. I do feel like I'm overlooking something though. Wheel gap shouldn't change that much I don't think.

Oh well, we shall see.

Well, however much lower your car gets, that's how much it's also taking off the top of the tire/wheel so that = more wheel gap.

24.3 - 23.5 = 0.8" So, half of that will come off the top of the diameter and and half will be on the bottom so... you'll be .4" lower and have .4" more wheel gap. You can't just go .8" lower unless you were to drop the suspenion .4", the tire/wheel has to remain a circle.

TheWanderer
06-11-2007, 04:43 PM
iDiaz, I'm pretty sure they are et37. I should have them by the end of the week. They were shipped today. I'm goin with 205/40 Kumho MXs.

amg, that makes sense. Truth be told I was posting in the midst of studying for a Caculus test so my brain wasn't functioning properly. And, I'll be dropping the car on M7 springs once I get the wheels and tires on.

KiLO
06-11-2007, 04:52 PM
Good point... I wasn't even thinking in terms of your et37 wheels. My RoJa's offset is 42, and I don't have any issues.

Interested to see how it turns out man!