Any reason NOT to run 225/45s on the street for the Miata, and, 8's or 9's?

I'm about to pop for some Konig Countergrams for the Miata, and my heart was all set on 15x9s and 225/45s.

Goodwin's site says street car keep 15x8s and 205s, but.... why?

Which begat the question, well, 225s on 8s with the et25 offset - would it rub?

I could be convinced to go 15x8 and keep running 205s, a little better tire selection if I decide not to run 200tw on the street, stuff like that.

Mostly daily driver, and I've only been getting 4 or 5 auto-x a year lately, 225s/9s not imperative, but I would like to see if I man up on some of the equipment and pull towards the top half of local STR.  And there are guys in stock NA/NB cars running re-71 at 195 and beating me, so....

Thoughts and opinions?

The wider you go, the more stuff you'll rub the tires and/or wheels on.  At full lock you can rub them on sway bars, brake ducts, or intercooler tubes, whereas at full compression you can rub the tires on the fender liners, shock towers, or fenders.  Nothing's guaranteed, it depends a lot on other factors like wheel offset, which model of tire, shock travel, bump stops, alignment, spring rates, suspension-geometry modifying parts (offset bushings or extended ball joints), etc, but the wider the wheels and tires the more likely it is to hit.  205s on 8s are usually OK, 225s on 9s will usually start to run into at least mild issues with this.  Most of this can be dealt with, but 225s are likely to involve minor compromises to streetability like not using full lock.

I'm running 245s BFG Rival S 1.5s on 15x9 Konig Dial-Ins on my Miata on the street. My fenders have a healthy roll/pull, I had to remove my R-package front lip (tires would catch it when turning), I chopped most of my front wheel well liners out and they rub the front front sway bar if I turn the wheel all the way. 

On a naturally aspirated street NA/NB, I prefer 205s on 8s.  Much wider tire selection.  For ultimate grip on track, 225s on 9s (under stock NA bodywork).  On 225s (which are all 200tw or R comp) a Miata will have enough grip to actually be less fun to drive on the street.

IMHO the best setup is a set of 15x8s with 205 Conti ECS for the street (which also make a great rain tire for track) and 15x9s with 225s of your choice for track.

225s on a 15x8 ET25 will probably rub on an NA without a pretty good fender roll.  NBs have a little more room to work with.

Weight and wind resistance.  The slightly smaller and lighter wheels will keep more of the character of the Miata.  And if mostly stock power, you don't need the extra grip for traction.  It's entirely possible the car will be quicker with the 205 on an 8" wheel.

Unsprung weight... you will be working you suspension harder with no real benefits on the street and even worse performance in wet. Tire compound and construction is way more important than width... more tire and wheel width adds unnecessary weight. You are looking at stock weight to 1-2lbs heavier for the wheels and 4 to 5 lbs heavier for the tires....so a 4-7lb increase of unsprung weight per corner. Plus 225/45-15 is a taller than stock tire... further slowing it's acceleration/decelleration in addition to the mass increase...

Not really.  If you want to autox, it makes sense to run 225s/9s and they work fine on the street.  You shouldn't really have rub issues with the right setup.  I had an STR Prepped NA on 9/225 combo and it was fine on the street.

That said, if you aren't also autoxing or tracking that setup, there isn't much reason to go beyond 8/205 on the street.  More options, especially rain/cold tolerant stuff.

15x8 w/205 ECS is a damn near perfect 3.75 season daily setup  (and autox/track rain tire)

Don't listen to the weight nazis.  The difference is really small.  Like less than 2lb per corner.

Dial in 15x8 12lb

Dial in 15x9 12.8lb

Azenis 615k 205 22lb

Azenis RT660 225 23lb

Vracer111 said:

Unsprung weight... you will be working you suspension harder with no real benefits on the street and even worse performance in wet. Tire compound and construction is way more important than width... more tire and wheel width adds unnecessary weight. You are looking at stock weight to 1-2lbs heavier for the wheels and 4 to 5 lbs heavier for the tires....so a 4-7lb increase of unsprung weight per corner.

It does weigh more, but that's significantly overstating the case.  More like half a pound for the wheel and 1 pound for the tire, per corner.

For a street car, I usually run 1" narrower on the wheel than the track fitment. My street Miata runs a 225 on an 8" wheel. Gives more compliance to the sidewall and I think it looks better. I also have another one that's turning into a street car that runs 245s on a 9". On track, that car runs 225s on a 9".

The big rubber does take away some delicacy - on our NDs, you can really feel the difference between the big 245s and the stock 205s. Looks awesome, grips like crazy (even with only 150 rwhp, because the corners don't care how hard you accelerated to get there) but what's going on at the contact patch is muted.

225s on a +25 15x8 will rub on an NA. They'll be really really close on an NB.

If I were to build another NA today, I'd go with 14x7 RPF1s. 

When I put the last one together, with Tein Flex Mono coilovers, FM sways, and Z1 Star Specs on OG Kosei Kis, it was razor sharp and performed better than just about anything I'd ever driven. A few years later I parted all the various mods and went back to OEM 7-spokes, but left the sways in because to me it wasn't worth the trouble to swap back to the pencil thin originals. I took it for a drive after the un-modding and realized I screwed up... all the car ever needed was the FM sways. Ten times more fun than it was with all the other goodies. 

aaaaaand now I'm on craigslist

There's a Miata in my own garage with a set of Konis and FM sways and 185/60-14 tires on stock wheels ;) I wouldn't call it razor-sharp, but there's a reason we fell in love with these things in the first place.

Unsprung weight matters, a lot.  They did not put those dinky little lightweight wheels on them by mistake.

Car is an NB, so a little more room.

Weight looks within a couple pounds all said and done, so I'm not terribly concerned there.

Sounds like a lot more rubbing on various components at full lock or compression with 225s; that doesn't seem terrible to me, but, I don't have any of that going on right now, and, I'd still like a bit of sporty character on the street. 

If the wider rubber mutes that sportiness more than a little, that would take away some of the fun of daily driving.  And I do pick up on nuances in handling, alignment differences feel night and day, for instance, not just "oh, yeah, that is better".

More thoughts on that aspect?  I know everybody is different, but, I've found that the "preponderance of the evidence" seems to work well for me when asking these kinds of things.

Run 205s on 7s for the street so you can have fun without having to corner at 1.2g. Have a set of 225s on 9s in the garage for when you want to win at autox. 

Toebra said:

Unsprung weight matters, a lot.  They did not put those dinky little lightweight wheels on them by mistake.

The 15x9s on my car weigh less than the OEM 15x6s did.

codrus (Forum Supporter) said:

Vracer111 said:

Unsprung weight... you will be working you suspension harder with no real benefits on the street and even worse performance in wet. Tire compound and construction is way more important than width... more tire and wheel width adds unnecessary weight. You are looking at stock weight to 1-2lbs heavier for the wheels and 4 to 5 lbs heavier for the tires....so a 4-7lb increase of unsprung weight per corner.

It does weigh more, but that's significantly overstating the case.  More like half a pound for the wheel and 1 pound for the tire, per corner.

I'm talking from stock (NA) - majority of the different factory 14x6 wheels weigh between 11 and 12 lbs from what I can find and a stock sized 184/60-14 Dunlop Direzza III is 17lbs or Toyo Proxie R888R DOT R tire is 18lbs. 15x9 Konig Countergrams are 13lbs and 225/45-15 tires run 22lbs on average...

I don't like any wheel or tire that is heavier than stock... if I'm upgrading my tires and wheels they will be at a minimum stock weight. I usually won't buy wheels unless there is a good weight saving over stock though. On my FR-S went from stock setup to one that was over 4lbs lighter with skinnier, slightly smaller diameter tires and lighter, 0.5" wider wheels and was a very noticeable change in ride quality along with huge increase in grip and wet/dry performance (because 205/45-17 Firehawk Indy 500s). Compound beats width... no need for wide tires and therefer wider (and heavier) wheels to support them for street driving if you are on a good tire compound with a better suited, less mass combo. Could even go smaller/ narrower in size to further improve ride quality while still keeping handling at the same level (provided the load rating is acceptable).

Everything else being equal, less unsprung weight is always a good thing to 'add'...

Personally for a street miata setup I'd run a 15x7 lightweight wheel (~11bs or less - like the Sparco/OZracing FF-1) with good 195/50-15 UHP street tire (Yokohama ADVAN Fleva V701, 17lbs). If you are tracking/autocrossing you will have a set of dedicated wheels and tires for those activities.

Wouldn't a tire that large turn a Mee-otter into a darting, tramlining, wild mouse kinda situation?

I was on track a couple of days ago in a 1995 with light 15x7s and a set of 195 Flevas. They like to talk. The goal was to keep them howling through the entire lap :) Loads of slip angle. Old school fun. 

It's best to think of unsprung mass as a percentage of total mass. That's why the Miata is fairly sensitive to it. It's why my classic Mini lives and dies by it.

Streetwiseguy said:

Wouldn't a tire that large turn a Mee-otter into a darting, tramlining, wild mouse kinda situation?

I run 225/45/15 Rival S 1.5s on a 15x9 wheel on the Manic Miata, which is street driven and autocrossed.  It doesn't really dart or tramline at all.  I love the way it drives.  It's got Koni yellows and GC coilovers and stiffer sways.

codrus (Forum Supporter) said:

The 15x9s on my car weigh less than the OEM 15x6s did.

 

How much more do the fat tires weigh and how much heavier is the big tire and wheel combo?

Just to throw in my combo, which I enjoy thoroughly on my NA with fender roll (slight pull?)... 

225/45/15 Maxxis RC1 on Advanti S1 15x9 for the track

225/45/15 BFG Rival on Konig Freeform 15x8 for the street

I like the look of the 225's, and the regular Rivals really don't have so much grip that I'm bored on the street. They're playful.  But I also have a turbo :)

Toebra said:

codrus (Forum Supporter) said:

The 15x9s on my car weigh less than the OEM 15x6s did.

How much more do the fat tires weigh and how much heavier is the big tire and wheel combo?

Dunno, I never weighed the original tires and those Michelins went out of production 20 years ago so there are no specs floating around on the Internet.  My 15x9s are about half a pound lighter than the OEM wheels, and if you assume that the michelins were similar to modern tires with the same nominal size, there's about a pound and a half more in the tire.  So maybe 1 pound heavier overall?

It's not anything I notice when driving it.

I had a 225/45 RS4s on 8" wheels on the '94 and they did rub occasionally going over bumps with the wheels turned.  Like the entry to a store or gas station or hitting the curbing at the track.  Wasn't enough of a problem to do anything about and I think a mild roll would have fixed it.  Went to 205's on 7" RPF1s for a while and I think that is a better street setup.

Just returned from the tire place with 225/45 Rivals on the 7" wheels this afternoon.  Track day on Monday.  We'll see how that works out.

As another data point, I rubbed more with 205's on a +25 15x8 then I did on a 225 15x9 +35.