Downsizing from 18s to 17s - Thoughts?
 

I recently purchased a 2009 RX8 Grand Touring and am looking to personalize it. My searches has led me to consider 17"x9" (45mm backspacing) Enkei RPF1 wheels with 255/40/17 Bridgestone RE11 tires. I've done a few searches and have not found many that have downsized their wheels besides those who race their cars. Is there a reason why those who race their RX8s use 17s instead of 18s? Is there a noticeable performance difference between the two sizes? I'm looking to place my order within a few days so any and all responses would be greatly appreciated.

Reasons for 17s: Those who track use plenty of tires, and 17s are cheaper than 18s, esp. r-comps, but also all tires in general; one can get the benefit of a virtual "low numerical rear axle" by choosing a smaller wheel diameter than stock, and then then the car is also, by default, lowered as well; the wheel-tire combo can weigh much less than stock; the 17" wheels are themselves cheaper than 18s generally.

Your wheel/tire size choice is IMHO spot on, argueably the 'perfect match' ...tire choice varies by application, RE11 are ok, perhaps not the best deal in UHP rubber. As an example (my fav for street use) http://www.discounttiredirect.com/di...mance&tmn=NT05

spin speaks truth...

ur 17x9 +45 is good choice. you should track with good results and feel...
if there is anything more i can add to it is that u'll lose more rpm's...a little more than series 1 rx8 due to having revised diff ratio (i believe 4.77 is the number thrown out there for series II)

not a big deal. but the acceleration gain in throttle response out of corners are real nice.

not a very streetable combo if u've gotta deal with driveways.

when choosing lowering springs/strut combo, chose wisely and be patient.

+1 that's the combo to run. I have the Dunlop Z1 star specs. as they are a comparable performance tire and at least $50 less per tire. Most of the autox community swears by them in ST classes.

One word of advice: There is very little inside diameter clearance between the front calipers and rim. Make sure the balance weights are glued on up against the spokes so they don't get clipped off by the caliper.

lol wow i was thinking of this exact combo of rpf1 and dunlops, any ideas how off the speedo would be from the size difference ?

I found this calculator to be incredibly helpful in determining those answers:
http://www.wheelsmaster.com/rt_specs.jsp

Gives the answers in laymans terms once you put in the numbers. Bookmark it! :)

I appreciate all of the feedback and I will be placing my order soon. Followup question - did those of you who run this setup lower your car and if so how much i.e. .5", 1", more? I've read somewhere that lowering an RX8 is counter intuitive as is worsens handling. Not that I have any firsthand experience with this but I thought that some of you may and can shed a little light. Thanks!

nice catch. i'm running on 17x9.5 and clears weights...but had to clip the SS brake lines to the upper arm as there's tire/line contact only under street use on full lock-to-lock turns.

forgot to mention that, but it can be an issue.

there's no need to "slam" an rx-8 for actual performance.

there's varying approaches on the matter... so there's more than one answer. but losing suspension travel from an excessive lowering spring choice would be the counter-intuitive one IMO.

-my take was to use RB springs (very very conservative 0.5in drop) paired with the 17s rpf1's. and i get around 1.2in drop total with that combo. its got decent spring rates and leaves other tuning options available to be paired with later... I, and a quite a few others like this approach to keep the car streetable when using multiple sets of wheels for track/street.
*a "sexy" stance isn't usually achieved with this route. lowering is accomplished, but sometimes (depending on setup) a fender gap may appear, giving less than appealing look.


-but then there's also people that go a bit more aggressive on lowering springs (i.e. 1.3fr/1.2rr; 1.2fr/0.8rr;etc.) and stay with close to stock or similar wheel/tire dimensions.

^^you have to wait for people who likes that tuning to chime in that can suggest good spring/shock/wheel/tire combo

-then there's also the expensive full coilover setup.
(my take on this is: stay away from this if ur a novice and won't take advantage of its full range adjustability. its complex,expensive, and many people simply dial in a setting too stiff and leave it for everyday use. that paired with a tuning less than optimal only leads to a premature suspension wear+more noises)

TrochoidMagic - I like to look of you car which is the look I'm going for - classy not ricey. Thanks a lot for informing me about the "things to look out for". I'm considering purchasing my wheels from tirerack which has them on their fitment list. Do you all think that their installers would know to be careful with the placement of the weights so they don't touch the brake lines?

Rotary 808 - installers will put the weights in the same place - right up against the back of the spokes on the inside. The problem is the design of the wheel, that part is raised and comes soooo close to the caliper that there's literally ~1/4 inch there (I have another set of 17" that has a different design wo/this hump there). On the back wheel there's no problem - the brake caliper is far smaller, but up front I was surprised when the weights were partially gone - worn off like being turned on a lathe...and deposted on the caliper itself! So next set of tires installed I hammered the weights down as much as possible - flattening them and all has gone well with little to no contact with the caliper. It's no biggie, just something to take note of.

If you're interested in these wheels we have them in stock in both

silver
matte black

Can't beat our club prices on RPF1's. Are you buying them as a tire and wheel package from tirerack?

Are you in Hawaii?

Thanks, Rishie

Endless Rotaries,

Yes, I will be purchasing both wheels and tires and live in Hawaii. Do you sell and would you be able to install factory tire pressure sensors? I'm looking for a ready to install set with wheels, tires, tire pressure sensors, centering rings, and lug nuts. PM me prices including shipping to Hawaii zipcode 96789. Thanks and I look forward to hearing from you soon.

I replied to your email.

AND I BEAT TIRERACK PRICE, NOT TO MENTION THEY DON'T HAVE BLACK. MUAHAHAHAHAHAHA.......

Thanks, Rishie

rotary 808,

thanks for ur compliments.

and as a matter of fact, endless rotary(rishie) was the person/vendor i'd happened on when ordering my rpf1's during the holidays. a good guy, and he'll take care of u.

and btw, you can use the stock lugs with the rpf1's. they are acorn(round) seated and work better with stock lugs. be careful with taper lugs as they can get loose if you punish the corners hard... like track use or the like.

BTW, what color is your 2009? after you get them on, if you took some pics please post them back on here.

My 09 RX8 is sunlight silver. Thanks for the information regarding the lug nuts. With this economy, every little bit counts. I'll email Rishie for a price without the lugs. Would you be post a larger picture of your car?

The best lugnuts to use (and recommended by this vendor) with these wheels, and the ones that will not cause seat wear on the soft aluminum are these, they have a slip ring at the base of the nut so when tightening the lug it does not grind on the wheel, plus they are quite lightweight... as well as acting as 20 wheel locks (nice) or as the web site says...

http://www.good-win-racing.com/Mazda.../21-1058c.html

"These are the patented design McGard Spline Drive lugs. Non-hex wheel lug which is both a light weight lug with more gripping surface area than the stock lug (to prevent lossening up under load), and a wheel lock. An RX8 takes 20 of these and ordering one of these kits includes 20 spline lugs and one tool. If you look really close at the picture above you can actually see the two piece nature of this lug by looking into the lug at the bottom of the picture. The part that touches the wheel (the "seat") stops turning and a bearing between that little ring and the rest of the lug allows the outer part of the lug to keep turning. What this means for you is that the lugs are not grinding against the surface of your nice new wheels and these lugs go on much smoother than any other lug choice."

EBB,

The wheels and lugs currently on my 09 are the factory 18s. So the clarify, since my wheels and lug nuts are both OEM products,TrochoidMagic's suggestion would be correct? I just want to be sure that I'm ordering parts that work together. Thank you for the suggestion and I look forward to your response.

The lug nuts for rpf1's just need to be conical seat style. That us what they call 60 degree taper seat. The link above is the right style. I was just making sure you did not confuse the round referenced above with spherical. Only other thing to make sure is that the tool will fit inside the recess for the lug nut. I had a 21mm hex open end lug nut that worked with the stock wheels but the 21mm socket would not fit into the rpf1. Problem was solved with some 19mm hex nuts. I don't care about looks so I get inexpensive nuts from dorman available locally. Also I need hex because I remove the wheels frequently and would lose the spline tool for sure.

i'm so glad you all posted.

OEM LUGNUTS = TAPER/CONICAL

RPF1 = TAPER/CONICAL

So suggestion is correct that the OEM lugnuts will work but THEY ARE NOT BALL SEAT.

Muteki's are fine or any conical 19mm lugnut. 21mm will require a thin wall socket.

Rishie

+1 for mcgard spline drive nuts.

Fancy lug nuts do nothing but empty your bank account.

"Fancy" lug nuts do several things. They help keep my wheels from getting jacked when traveling to various unsavory parts for track events, they keep random torque wrench wielding tech line people from messing with my wheels, they might save a few gram's weight, and to boot I like they way they look vs. acorn nuts.

I'm sure you spend your moeny as you see fit, why do you feel the need to comment on simple things others do? Stick to more significant things.

Eric has plenty of very significant knowledge and has shared much more of it with us then almost anyone else on the board. Ease off him. There are a ton of rip off lug nuts that aren't worth the money.

The only lug nuts I would spend money on are the McGards. The mating face is separated from the spline by a bearing so you get solid torque without galling the Aluminum rims. They do a great job of protecting your rims from getting torn up by your lug nuts the way the OEMs do. As far as weight savings, you're stupid or have too much money to buy lug nuts just for weight savings.

Why?

Because you'll often find misinformed people on these forums that spread incorrect information. These people may have honest and genuine intentions however that doesn't make what they believe to be true. I believe my role is to offer additional input which may confirm, adjust or may be to the contrary of the information shared.

An example would be this: You can find a good lug nut for a little over a dollar if you hunt around.

Another would be this: if you remove/replace/rotate your wheels often, invest in a quality wheel stud and treat your lug nuts more like a consumable. Boogered threads on a lug nut is more often than not the reason for a mis-thread----not a bad thread on a wheel stud.

Avoid aluminum lug nuts unless you really like the fancy look. They are weak(er) and can more easily become stripped.

Here is another one: If you've upgraded your suspension and grip to allow for better performance at your local road course, you should closely inspect the wear pattern of your front brake pads. Many people move to R compound tires but don't think about what how this influences their braking dynamic. Why look at your pad wear? Because the stock front brake calipers can and do flex. This flexing leads to permanent represented in an "opened up" caliper(s). This leads to (a) a less optimal relationship between your brake pad and rotor (lessening your car's braking ability), (b) costs you more money because you are only using a portion of your brake pad and not the entire pad and most importantly (c) leads to beliefs that you must invest a bunch of money in aftermarket front calipers and rotors. The simple fix is to purchase a new set of front calipers from Mazda. A person needs only to look closely at their used brake pads to confirm the condition of their calipers.

Since we are talking about wheels and tires it would be noteworthy to suggest that different sized wheels and tires will change your alignment. See it all the time. ALL the time. Spend a few hours on this forum and learn a little about suspension setup and take your car with new wheels and get a new alignment. TELL the alignment shop what you want or you'll get the factory specs. All of these little things are learned from lots of experience and much money and headache can be saved if you talk to someone who has been there/done that.

Happy Rotoring all,