having recently stepped out of a E36 M3, into the RX8, I'm still suffering from sticker shock of good rubber for the OEM wheels.

The local tire place offered 17x8 Kosei K1-TS to me for $89/ea. I was hoping to put some 235/40R-17 tires on these wheels, but don't know if there will be any detriments from going to a small diameter wheel?

Any opinions?

 

You'll get a cushier ride and a bit less initial steering precision and far less expensive tires. BUT the 235/40/17" tire is absolutely the wrong size for the 8. Go here http://www.miata.net/garage/tirecalc.html and you'll see you'll be 6% off on the speedo and .8" lower as a result. Might be good for track, but not daily drive. Try a 245/45/17 for example.

 

heh, right after I posted I went to miata.net to do that calculator size. thanks though!

I feel like I should go with a wider wheel at the very least, with wider tires, but am still flip flopping between 17x8, 17x9, or just another set of the OEM wheels (cheapest option temporarily, really)

 

Right now I have these with my track r-comps. They were only $135 in 17"x9" @20lbs see pics here in this thread https://www.rx8club.com/rx-8-racing-25/post-pics-your-8-race-trim-138938/

Doing it again I'd get these which at 15lbs are super light, strong rim technology and decent looking and 17"x9" here http://www.good-win-racing.com/Mazda...t/60-1290.html

 

I'm going to come off like a brat, but:

1) the link to that thread, and pictures of your car inspired me to post this thread.
2) those enkei's are the exact wheels I want

Glad to see that I'm thinking on the right track, and thanks for the insight!

for the next track day, I want my near stock RX-8 to completely hound my old E36 M3 (which was already modified, but has 17x8.5 Kosei K1s, race rubber, sway bars and TC Kline Double Adjustable coilovers).

The new owner of my car and I are going to swap cars on the track for comparative analysis. I want them to see why I moved "up" to the RX-8:P I can't have the new car slower around the track than the old car!

 

Your welcome, good luck, I think you'll not have too much of a problem against the E36, but it'll be fun anyway!

 

I opted for 17" track wheels in order to reduce tire costs as well. I ended up buying a set of 17"x9" +35mm 5Zigen FN01r-Cs and 255/40-17 Toyo RA-1s as a package deal for ~$1400 shipped from Edge Racing. That included mounting, balancing, hubcentric rings, lugnuts, and center caps. Apparently they're still running the same sale, and you can get this exact same wheel in black or bronze for $159 each.

I'm a big fan of the RP-F1s as well (had a set on my old Miata), but for $80 less per wheel I couldn't turn these down.

 

Very cool site.... thanks, dugg

 

I like the sound of this deal!

good deal! Did you have to call them to place the order? I can't seem to find 17x9 as an option under wheel and tire bundles.

 

Yeah, if you put in an RX-8, it doesn't offer 17x9 as an option.

I placed the order online while Edge was closed for the holidays, so I had to play around with their website a bit until I could get the combo I wanted. I ended up putting in "my" car as a 2005 Ford Mustang... which shares the same bolt pattern and uses similar offsets. Do this, and it should pull up the 17x9 +35mm as an option.

 

There is a higher offset version of this same wheel that would be a better choice, but they aren't offering the $159 price for it. I'd call them up and cry until they hang up or give you the $159 on the higher offset.

Funny, I'm parting out my E36 with TCK DA Konis, SSRs, RD bars, etc. getting ready to buy an 8. The eight, bone stock, feels really close to how my BMTrouble-You felt all done up.

That's a crazy good deal. I'd probably go with it.

Read over in this thread:

https://www.rx8club.com/showpost.php...0&postcount=21

https://www.rx8club.com/showpost.php...0&postcount=31

I think the 17x9 +45 RPF1 is probably the best all-around wheel for the RX8, as long as you don't want to run certain BBKs down the road.

 

That's a great looking wheel for that color 8. Adds that 'mean' ...opps that is "means business" look. Very stealthy!

 

that's how I felt when I took my completely stock (including tires) RX8 out on the track. It didn't feel as fast, but everytime I looked down at the speedo I was exiting turns faster than I had ever in my E36 M3.

the RX8 just makes it seem so easy.

 

I think a +35mm works just fine on these cars. I ran 100+ track miles at MotorSport Ranch today, and the car performed flawlessly with the above combo. The +35mm wheels add another 16mm of track width to the car at both ends over a +43mm, and I had no rub at all with my unrolled fenders, even at full suspension compression.

 

I always worry about upseting the suspension/steering geometry, wear on bearings, stuff like that. Maybe being overly cautious, but can't rationalize taking chances for a few bucks savings, esp. on track where stresses are highest the car will ever see, and your life is on the (racing) line lol.

 

Also watch out when you lower the car.
My cat scratches now with the height of 17" wheels.

 

when you widen the track without an increase in spring or sway bar rate all you accomplish is more body roll from the resulting longer lever arm

then there's the scrub radius effect ...

 

what size 17" tires do you use and how much have you lowered?

I lowered about 25mm only with nearly stock diameter tires (275/35/18) and I found it was ok "except" going into parking garages! Even those slight /\ when you are going down a level and my cat was mashing the cement. That was a surprise the 1st time and so I quickly learned to then go over those /\s sideways as much as possible (one wheel at a time)!

spin

 

Widening the track also results in a decrease in tire loading for any given lateral acceleration, also due to the change in lever arm length.

You do make a couple of good points, however.

 

Mine is 25mm too