Wider tires on stock wheels
 

I have looked through tons of threads before deciding to post this questions to the fine folks here. I am looking to put some new rubber on the stock wheels and was looking to hear some input on the pros and cons of going to a wider tread in terms of handling characteristics, fitment, etc.

After looking at a lot of feedback between RS3's, Pilot Super Sports, Rivals, and ZII's I think I am leaning towards the Dunlops.

However, I an torn between tires widths. I have seen that the Dunlops have a naturally wider tread due to not tapering the way the stock Primacys do, but what about going wider? 225/45 17 or even 245/40 17 which is almost a full inch wider?

If I chose the 245/40 is there a problem installing them on a rim as narrow as the 7" stock? And, what does that do to sidewall deflection under load?

I am looking to get into AutoX and some track time this year (first time ever in my 44 years on this planet) and I am just looking for a little guidance.

Thanks in advance.

I've seen 225/45R17 Super Sports on the stock wheels. They fit very well. Not too beefy at all. They fit very nice and proper.

maybe @Racecomp Engineering or @CSG Mike can give you a good answer on this?

use 215. Any wider and you're gonna lose a lot of tire feel. 215 is the widest Z2 that is specified as being usable on a 7" rim.

Most 225/45-17 (ZII included) are OK on 7" - 8.5" http://www.tirerack.com/tires/tires....el=Direzza+ZII

I'd probably still go 215/45-17 though for reasons stated above, and also 2 lb. lighter, and the 225/45's are taller (slightly worse gearing, slightly higher c.g.). But could go either way. 245/40-17 definitely not a good idea...

Thanks for the great info guys. 215/45 it is. It is always good to get second and third opinions, especially from more seasoned users.

I have a 245/40/17 on the back of my car fits on the rim easily and looks very chunky.

fits in the guard easily too, since then i upgraded and have a 255/35/18 now still fits in the guard with plenty of room

I have 225/45/17 PSS on stock wheels and love them!

My winter tires are 225/45x17 on stock rims. They handle better than stock.

I think 225 is the right width for this car. Looks good and works better than stock 215.

Wider rim would make the tire a bit sharper in turn in and a bit harder riding.

17x7.5 is ideal wheel size. 17x8 will also work with 225 section.

Just by the by, 10 mm is about a third of an inch and that's nominal. Actual tire section is likely hardly different between 215 and 225. This 10 mm is divided between the inside and outside tread edges. 5 mm each....

not all 215 are made equal. You guys are not doing your research like the OP is. He is planning on running a tire that runs wide. His 215 Z2 is wider than a 225 winter tire or PSS.

Just because someone mounted it on a 7" wheel doesn't mean it FITS. Minimum wheel width for that tire is 8". Bad idea to spoon it onto a stock 7"...

How much of a difference in grip is there between a 215 and 225? Basically I'm trying to weigh if the overall grip outweighs the loss in steering feel.

Did a little research on Tire Rack on sizing:

(all XXX/45R17 sizing)

TIRE / SECT WIDTH / TREAD WIDTH
OEM Primacy / 8.4 / 7.5
MPSS 215 / 8.4 / 7.7
MPSS 225 / 8.9 / 8.2
RS3 215 / 8.4 / 7.9
RS3 225 / 8.9 / 8
ZII 215 / 8.4 / 8
ZII 225 / 8.9 / 8.2

Both on 7" wheels? Probably not as much difference as most people would think. Width does generally increase lateral grip, but not necessarily for the reasons most people assume. Contact patch area will be about the same for both, but the 225's will be a little wider and shorter. But this effect will be reduced a bit with both on the same 7" wheel.

Figure the improvement will almost certainly be less than the ratio of widths suggests, so less than 5%. Nothing you'd feel, and any improvement in laptimes from increase lateral grip will be offset to some degree by increased weight and slightly worse gearing from taller tires. Conceivable that 225/45-17 could be *slower*.

Take the numbers with a grain of salt; Tirerack just republishes manufacturer numbers.

A little, but not much.

Stick to the 215. It's already gonna be low on steering feel because 7" is the minimum rim width for the 215. The 215 on a 8" would likely be faster than a 225 on a 7", because the contact patch will be larger.

I will say that I bought 225/45/17 PSS purely to have a meatier look.

@Ninjin is running 225/45 PSS's on his stock wheels. They fit great. Not too much beef at all, but still some decent curb check protection.

Thanks to the OP for this question. I'm in the very same frame of mind as I consider upgrading tires and/or wheels.

I've been to one HPDE session with the car bone stock; and obviously wasn't pushing the car too the extreme limits, but I didn't like the way the stock tires (Primacy) felt. In fact, I lost traction and spun off the track once. A lot of that was my inexperience, but these tires aren't the stickiest either.

My plans for the car are to stay NA for now, do at least one more HPDE and hopefully 3-4 Auto-x events in 2014. Once I get closer to warranty expiration, I will modd exhaust and tune.

For now, I'm considering upgrading the tires (looking at the Michelin Super Sports as I want a tire that gives better performance than stock, but can also do double duty as a daily diver...can't justify separate track/auto-x set of tires/wheels at this time, so I need the tires to be at least reasonable in the wet as we do get a fair amount of rain here). I've also considered upgrading wheels to 17x8 or even 17x9 with a 225 or 235 width tire.

Now I'm wondering if just going with either a 215 or 225 tire on the stock wheels for 2014 and getting some more events under my belt and then reassess.

My question: at my relative low skill level, is it really going to matter if I go with 215 vs 225 if I stick with the stock wheel? Would anyone experienced advise me to just drive the stock rubber until they're toast and then upgrade to better tire?

Stock rubber is a low rolling resistance tire with soft sidewalls. The Primacy HP gives up grip abruptly as the sidewall rolls over and plays dead. It works fine up to that point. Better tires do not do that. Stay well away from any LRR spec tire if you want decent performance.

Everybody who fits better tires likes the result.

Michelin Supersports are probably the industry leading tire in that category at present.

215 and 225 are roughly equivalent sections. It is unlikely you would notice a difference. I like the look of the 225 better so I went with that. The 225 is more suitable to developing driving skills, especially on the stock 17 x 7 wheel, because it has a slightly taller sidewall and will bulge slightly more on that narrow wheel. Both of these characteristics give a more progressive breakaway and the slightly shorter and fatter contact patch will make initial turn in a bit less critical feeling as the tire will give a bit more as you input steering lock. As oversteer develops you will find the counter steer a little easier with the slightly fatter tire. The narrower tire will feel slightly sharper and on that narrow rim will react more quickly.

I'd fit 225/45 x 17 Michelin Supersports.

I've just bought a set of OZ Alleggerita 17 x 7.5 in graphite silver with Michelin Pilot A/S 3 tires to achieve the same result but with cold weather in mind. If you routinely drive on summer tires at temperatures below 40 F then consider this particular top line all season tire seriously. If most of your driving is in proper summer temperatures then the Supersport is going to be hard to beat.

In my experience, a wider tyre than is recommended on a wheel experiences more roll in the corners.
If for example, a tyre manufacturer recommends a tyre on a 7.5"-8.5", 8" optimal, I certainly wouldn't run it on a 7". I probably wouldn't run it on a 7.5". I would run it on a 9" if I had to.

You can fit a 215/45, 225/45, or 235/40 Dunlop Z2 on the stock rims. The 235/40 is the favorite size for this tire for the autocrossers, though the stock offset cuts it a little close.

Since the OP is starting out, I'd say go 215/45. I have them and they're wider than the Primacy, but they're not THAT much wider.

Michelin is OK with a 225 on a 7x17 wheel.

You should not run a 235 on a 7x17 wheel as minimum recommended for that size is 7.5 inches.

Autocross is highly specialized and low speed, emphasizing turn in and rotation where sidewall roll is actually an asset.

For street driving or occasional track driving stick to 215 or 225 would be my advice.

What brand tires did you use with the stock rims for the 245/40/17

Are those 245/40/17. On 7” rims. If so what tires did you use

I really do not suggest putting a 245/40 on a 7" wheel. It's not going to look good. A 225/45 will work on a 7"

245/40/17 should go on a 17x8" minimum. or better yet, IMO, 17x9" wheels

Im running 245's on 9" wheels. They fit right.


With that said, and I don't know where the thread is, but some guys were using a 245/40 on a 7" for track use.

I ran a 245/40r17 Z2SS for autox and daily driving in 2016, on a recomendation that a local guy was doing well with this wheel/tire size and that Z2SS had a stiff enough side wall to handle the narrow wheel.

It really kinda sucked at times trying to manage tire preasure to maintain the side wall and all. The ocassional fast and hard transition where the side wall quickly flopped from bulging-out to stretched-in on the rear outside tire under heavy loading was obvious from the driver seat and getting used to that grip-flop-grip transition took some effort.

haha, leave that combo alone

God I love this forum! No subject is too much to dissect down to the last millimetre! I'm pissed that the UK don't get the "new" P4S in 17inch!

I have been obsessed with tires and wheels for as long as I can remember. I used to just read the lists of tire sizes, that used to be in car magazines, trying to find rare and unique sizes. Now combined with wheel offset, they are fun mathematical "fitment" puzzles. They calm my brain.


You are talking about the new PS4S? No 17, that sucks! I am planning on trying them next, thought in a 18" size.

19" is the smallest diameter available in the UK.

Yeah, no PS4S in 17 or 18 sizes in all of Europe, even though supposedly Michelin is european brand. Only for 19,20,21, with wished normal sizes sold at US only (for now. I hope that maybe in spring things with availability will get better). Due size & weight shipping tires overseas + import charges will at least double the price, they are not THAT much better. What's available in common sizing in EU are non-S MPS4 ones, but from my experience compromise in them is too much moved to street, grippy, quiet, wonderful wet traction .. but easy to overheat on track, so not considering "normal" MPS4 anymore, as i need dual-purpose tire. As of now, "old" PSS or AD08R seems better choice from available here.