15 inch wheels for 90 CRX

[REPPHD]

I am running 14X7 with 225 Kumho's. Anyone tried successfully to put 15 inch tires on the car? My crew suspects there is not a chance in fitting. Any thoughts or suggestions.

[darthmonkeyIT]

I believe I have heard of it being done. 225's in Kumho's are skinnier than 225 Hoosiers and I have heard (HEARD mind you) that if you flare the fender wells a bit and accept that you can not turn near wheel lock you can get 225 R15 Hoosiers on. A 205 Hoosier is about the width of a 225 Kumho. Same goes for the Hankook Z214's at 225 compared to a Hoosier 205.

There might be some rub though on the rear trailing arms which is why I have also heard in order to be able to run 225 R15's you need a large spring rate in the rear (heard 1000#'s). This is to prevent the car from leaning over the tire and instead lean the tire over with the lean of the car. It is also nick-named knife edge driving at that spring rate because the car will tend to hook around corners but if you get it wrong you end up pointed the wrong way.

[raffaelli]

Hoosier 15 225 will fit. A fast crx in the northeast runs them. Not sure what the offset is. He does not run 1000 in the rear.

What performance gain are you looking for over the tire 14 225?

[Chip42]

as above, you might need some spacer or rolling the fender, but 15" hoosiers are actually very very close to the same rolling diameter as their 14s (less that 0.1" difference 225-225 and 205-205) so if you can fit a 225 R14, and MANY have, you can fit the 15s as well. 15" stock wheels from the integra work (basket weave and daisies) and Phil's Tire Service and TrackSpeed Motorsports sell a 15x6 DForce wheel called the CR6 which will fit your car, too.

[REPPHD]

thanks guys.

I run 225 50 R 14 at 22.8 OD, 9 inch width KUMHO which are a bit wider than Hoosier

225 50 R15 would be 23.7 OD sames width.

At RA I run the 4.73 gears. Now I know I could go back to 4.11 which would change the rev pattern and that is an option for next year.

I ran 2.50 on Saturday, did not try and go fast on Sunday as it was my last race this season anyway and I was not running enough to challenge anyone in points. I think i could have run about 2:49 or a bit better with what I have. I run 650's in the back springs and my motor is good, but has no piggyback just a 6 year old chip at this point. In going through the carousel and Kink I would like to up my speed there and I have been pretty conservative there so I know I have time to make. My thinking with more OD, I would have less revs so be in a better power band to go into Canada and also pick up some advantages. Right now I do about 7000 into 1, 7000 into 5, but best into 12 was about 6700 on Saturday and maybe 6300 on Sunday.

So I think what you are telling me is it possible; we fixed the rub on the Kumho 14's early on; The 15 inch wheels I think are good at about 11 lbs are 35mm offset (miata). Bigger tires weigh more, but wheels keep total unspring weight gain to a minimum.

If I want to run with Midwest Council in the top three I have to be 2:48 and we did see 2:47 and even faster this year with a couple of national miata guys.

Further thoughts?

[Chip42]

225 50 R15 would be 23.7 OD sames width.

225 45 R15 hoosier is 22.9" diam.

At RA I run the 4.73 gears. Now I know I could go back to 4.11 which would change the rev pattern and that is an option for next year.

taller tire is like going to a smaller gear. doing both would be murder unless you stepped down the gearbox and even then it rarely works out well as the spacing tends to increase in the bottom of the box. what you are talking about is a ~10-15mph change in 4th gear speeds at 7k RPM, and less acceleration on the way there.

So I think what you are telling me is it possible; we fixed the rub on the Kumho 14's early on; The 15 inch wheels I think are good at about 11 lbs are 35mm offset (miata). Bigger tires weigh more, but wheels keep total unspring weight gain to a minimum.

just be careful, Miata wheels are 54mm center bore, honda is 56. also, most of the Miata wheels I've seen are +45mm offset. spacers can take care of both problems though.