Optimal tire size for DD and canyon driving?
 

About to get a set of Summer PSS and before I stick with 215/45/17 I was wondering what the consensus was on the "optimal" tire size for this car was. (my tims are 17x7.75 if that matters)

The 215's are thin, but the PSS should offer good grip still, right?

225's would be slightly different without upsetting anything - slightly more grip, slightly more beefy look (but still thin).

Then there's 235's - but will they kill my gas mileage completely? Or ruin steering feel?

Oh - running everything stock, so stock suspension/ride height. 235's might not even give me "the look" without lowering the car.

Thoughts from the masses?

235s seem a bit wide for that rim size, but maybe that's just me. I'm running 225s PSS on my 7.5" wheels and am pretty happy with those so far.

I'm a Dunlop guy. I like the DZ101. It offers a good mix of grip and tread life optimal for a DD.

You're in socal. Get a stickier tire.

PSS, 225

Twice the performance of the Primacys, a solid safe great handling tire.

For me, I really like the 205/45-17 size Max Performance category tires I'm currently running (Kumho LE Sport) on my still stock suspension FRS... much more optimal than the stock tire size for a 7.5" width rim. Diameter is ~.3" less, so speedometer will be a little off, but in the proper direction (reading faster than you are actually going.) Benefits is you do gain better acceleration/deceleration when on and off the throttle from the better 'gearing', chassis agility is noticeably improved, CG is lowered by half the diameter decrease (So it's ~.15" lower than stock), and you have tire mass equal to or even less than the stock tires (= better ride quality).

The stock tire size for this car probably should have been 205/45-17; it fine tunes the chassis even more and quickens its responsiveness. The last thing you want to burden this car with is heavy boots (big, wide sticky tires)...you really notice the loss in agility. What you want is lightweight "track shoes" (narrow somewhat sticky tires) that maximize the chassis's potential. A maximum agility setup trumps a setup with higher traction but with more numbness in the chassis response...

I run a 245/40/17 (17x8 wheel) Starspec II in the summer, OFT stage 2, Perrin Intake and I still get 30mpg in the summer on average, and 33 on the freeway. Unless you change your driving habits you shouldn't see to much of a change in mpg going to a softer 225 tire. But if those few mpg are important then maybe a 215 is what you need.

I ran 205's on my 2200lb Hondas but wouldn't go that small on this car if I was also looking for grip feel. 215 min, 225 DD imo, but I'm also very happy with the DD feel of my 245/40s.

Go here for calculating tire dimensions: http://www.miata.net/garage/tirecalc.html

245s on 17x9 for an aggressive turbo car and I do fine. 22 mpg on e85 at 450+whp. Cheap ventus v12s too.

I should note that the 205s I'm running have a wider tread than the stock 215 Michelin Primacy HP's along with better traction in all conditions, and simply unreal wet weather ability - contact area is both larger and wider than stock. It is almost just as planted in the dry as it was with the 215/45-17 Extreme performance track tires on 17x8 +36mm Kosei K4R's, but with better agility and steering feel. In the wet though, nothing I've tried before comes close... It feels more stable than the stock tires do in the dry and is loving this 40'ish degree wet weather we are having... grip grip grip with no complaints.

205/45-17 on 17x7.5 wheels:

http://vracer111.smugmug.com/photos/...-LFQvKZt-M.jpg

@Vracer111
That's awesome that you have a 205 that works well for your needs.

I'm a little surprised that a 205/45 is wider than a 215/45 I think the sidewall to sidewall measurement is smaller by about .4", but perhaps it's because they are a little stretched that the tread width is larger?

Got this from tire rack, I think it explains it...and I learned something today!

http://www.tirerack.com/tires/tirete...e.jsp?techid=7

With your wheel width of 17x7.75, I would either go 215/45/17 or 225/45/17. I'm running the same tire in 215/45/17 on a 17x7 wheel. The level of grip is excellent for street driving. However, it will leave you wanting more if you decide to autocross/track.

I wouldn't even consider the 235/45/17 size. The thicker sidewall would take away steering response and the larger diameter would make acceleration more sluggish with the taller gearing.

Oh, and with the PSS, I would recommend running lower pressures than stock for better grip. 31 or 32 psi is working well for me.

Keep in mind that the actual width of the tire varies per manufacturer/tire model, e.g. not all 225s are the same width..

Hoosier A6 tires.

I don't think I am going with 235's, but if I did, I think they would be 40 series - I'd have to run it through the calculator to see if that worked. I wouldn't want a taller tire.

Leaning towards 225/45 at the moment. (ok, I realize this might be taller than a 215/45 on a 7" wide wheel, maybe, but it would be as tall as I'd want to go.)

Won't be doing track days or autox. If I ever decided to, I'd get a separate set of wheels/tires.

I don't notice any loss in steering response or feedback at the track on 235/40/17, but the sidewall on these tires is very stiff (NT05) and they're mounted on 8" wide wheels.

Also note the reduced sidewall makes the fender gap more noticeable on stock suspension.

https://farm4.staticflickr.com/3835/...1745abc6_b.jpg

I'd go with 215 or 225 in your position.

The sidewall to sidewall measurement has an industry standard, and this is measured and repeatable between manufacturers.

The tread width does not have any standard, and this is where you can see different contact patches for the same size tire between different styles of tire (winter vs. all season vs. summer) and manufacturers (dunlop vs. nitto summer tires of the same size).

http://www.tirerack.com/tires/tirete...jsp?techid=194

Note section: Section Width.

So a 225 will always have a sidewall to sidewall measurement of 225mm (see Section Width below), but the tread of two 225 wide tires can be different (see Tread Width below).

http://www.tirerack.com/images/tires...dimen_2010.gif

UPDATE:

Ok, so I decided to go with 225/45/17 on my 7.75" rims. Michelin Pilot Super Sports.

$70 rebate going on now. Got a decent deal locally. They had to order them but will get them Monday. Looking forward to the newfound grip but also the ability to drive my car in the rain this winter.

Debated for a while between 215 and 225, but in the end its not going to have a huge impact and I'd prefer that tiny bit more of traction. With the wider than stock rims, I figure overall height/diameter is close to stock.

Ok, 225/45/17 Pilot Super Sports = super happy. :D

Should have done this 2 years ago...

This what run and extremely happy.