Hey guys. I've done quite a bit of research but I'm still unsure if I can fit these. I have an '05 R53 and I'm looking to run 15x8 Konig Wideopen's and hopefully 225's front and rear. Is this possible to do without much rubbing? I will be doing many auto x events so I don't want any rubbing during hard cornering. I have Megan coils with built in front camber plates and H-sport rear lower control arms. Any help is appreciated, thanks!

 

Which Wideopen rims are you considering, they come in offsets of 20 and 25mm. 25mm would be better and stick out less. Should fit your suspension.

225/45-15 tires would be a good choice for 15x8 rims with 225/50-16 being second choice but tire selection is your greatest deciding factor.

Pick a tire to suit your use then use the size it comes in.

 

I'll be going with +25mm. I haven't decided exactly what my alignment will be like but it will be auto x oriented. It looks like these will work fine then?

 

Yes, offset 25 is OK.

What class autocross are you considering? DSP, STX, SMF?

You want to try to mod your MCS to the limits of the class and be legal.

For alignment-

Front camber- as much negative as your camber plates will allow, more is better, at least -2.2 or more

Front toe- you can try 1/16" toe out for quicker turn in response. As you go with more toe out, you may get additional tire wear when street driving and slight twitchiness.

Rear camber- set to about 1 degree less negative than front or about -1.2 degrees is fine. More negative will increase understeer.

Rear toe- set to 1/8" toe in for straightline stability.

What swaybars are you using? Try 19mm three hole rear bar set to middle setting then adjust. The more stiff the rear bar the less understeer you get up to the point of getting oversteer if too stiff. You can leave the front bar alone or you can upgrade both with soft setting for the front and medium to stiff setting in the rear, then adjust.

 

Wow, thanks for that. That helps a lot! I'll end up in SM. I've really been modifying the car to my preferences without regard to which class I'll be in. I'm not really worried about being competitive in my class, I just want to have fun and learn the limits of the car.

I currently have an H-sport 22mm rsb and stock front bar. I should have mentioned that. I'm running it on the softest setting as I am a bit concerned with lift off oversteer. I understand how to control it, I just haven't had much experience with it.

 

OK,

For SMF class you can run street or R compound tires in 225/45-15 or 225/50-15.

225/45-15 is the better tire size, fits the 15x8" rim, has a stiffer sidewall and smaller tire diameter for lowered gearing.

Depending on which tire you choose you may not have a choice of 225mm wide tires.

If you are not trying to be competitive it's nice to try Extreme Summer tires to begin with because you can drive to the event and race and use them for street use.

BF Goodrich Rival are the tire of choice, easy to drive and control.

Rear swaybar on soft is fine. Wide front tires will give you more grip as does more negative front camber, both help to reduce understeer.

Most times the MCS gets into SMF class due to a reduction pulley on the supercharger that increases boost/power. Otherwise you can also change fuel injectors, intercooler, headers, intake, ECU map, throttlebody, etc.

Racing harnesses like Schroth quick fit are nice, they clip in fast and can easily be removed/stored for street use.

 

I was highly considering the Rival so that's what I'll probably end up with. I have a 15% pulley which is a main reason I'm in SMF. I'll continue to modify it so it's nice being in a class that allows it. In the next few weeks I'll have a roll bar/seats/harnesses but those quick fits look like a great option for stock seats.

 

Hmmm..... Good luck on the rear with the 15x8 at 25mm offset and 225mm rubber.

I'd expect interference between the outer edge of the tire and the fender liners at the 10 and 2 o'clock positions.

The front end, I'd expect no problems.

Here is why. Hopefully I am mistaken.

Cheers,

Charlie

 

Yeah an et25 does sound kind of low but I guess it would depend on ride height and spring rates. What spring rates are you running? I believe Craig Wilcox is running a 15x9 Rota up front but not sure on offsets. And that's on an R56.

Oh and don't do 1/8" toe-in in the rear. You'll never get that car to rotate properly. We run 0 toe in the rear. RWD cars are commonly toed in at the rear to get power down better and make them easier to handle coming out of corners.

 

7KG front and 6KG rear.

 

Anyone know if I'll need spacers in the rear?

 

Baker, have a look at Craig's post in the "Mini Autocross results" thread.

Cheers,

Charlie

 

https://www.northamericanmotoring.co...ml#post3901580