Tires for stock-class auto-x...?

[MINI-Fit]

Originally Posted by dj_oatmeal

Can I run Falken Azenis RT-615 205 50 15 in the front and stock 195 55 15 in the rear and still be legal in H stock? I've read the rules and it makes no mention of tire size front to rear but don't want to buy them and be DQed at the event next weekend.

It is fine for H Stock.

In H Stock class you can run any size tire that will fit without rubbing that might cause a safety issue and any DOT approved tire from R compounds like the Hoosier A6 to Kumho V710 to Toyo Ra1s or any street tire like the Bridgestone RE-01R or Falken RT-615 like you mentioned.

You can run different size tires front and rear but the handling will be different and since the sidewall is different as well you need to fine adjust the tire pressures to get the handling you are looking for. That staggered setup will give you a little more grip in the front and a little less in the rear depending on your tire pressures and other suspension and alignment settings.

In Street Touring classes you have width limits for tires but many of the other classes are wide open. Mostly you are limited by wheel width limits and wheel arch clearance- some classes allow fender rolling while others allow for wider arches/fender kits.

[dj_oatmeal]

Thanks for the feedback. Order placed. Car is stock at this time. I plan to measure tire temps across the face to try and dial it in before I run out of runs. I ran the first event on the stock SP31s with 41psi on all four corners and found the car to be fairly neutral other than inside wheel spin while accelerating out of corners. Missed out on third in class by .109 sec to a Scion Xa. Hoping a little more seat time and the front tires will not leave me so close next time. Remove muffler and add a short length of pipe like I saw in another thread here before next weekend if I get time. H stock legal from what I can interpret from the rules. After that camber bolts or rear air shocks will probably be next depending on how the car feels.

[mrFroge]

Originally Posted by dj_oatmeal

Can I run Falken Azenis RT-615 205 50 15 in the front and stock 195 55 15 in the rear and still be legal in H stock? I've read the rules and it makes no mention of tire size front to rear but don't want to buy them and be DQed at the event next weekend.

As long as you are runnng DOT approved tires, it is legal in stock clases to mount any size that will fit onto a car's legal wheel.

[dj_oatmeal]

Tires and camber bolts will arrive tomorrow. The local exhaust guy quoted me $65 for the replacement pipe to remove the muffler. I decided that was to close to the cost of the alignment at $70 to not get the alignment instead. I figure the alignment is worth more time on track than the weight savings.

Can anyone recommend alignment settings as well as tire pressures for the Azenis? The alignment needs to be a comprimise between streetablilty and track performance. Thanks.

[sl0wp0k3]

Originally Posted by dj_oatmeal

Can anyone recommend alignment settings as well as tire pressures for the Azenis? The alignment needs to be a comprimise between streetablilty and track performance. Thanks.

front:
camber: max negative (~negative 1 degree)
toe: either 0 or 1/16 inch toe out front for better turn in.

1/16 inch toe out should not affect streetability, tire wear increase is minimal.
camber should also not affect streetability at all, rears are already 1.5 degrees from the factory.

rears can't be adjusted.

tire pressures are something you need to test out. get some chalk, mark the sidewalls up to the tread, start around 45psi or so in the front, do a run, and bleed 2psi, and repeat until the chalk disappears up to the edge of tread(you can still see chalk on the sidewall up to the tread). then play with rear pressures to tweak balance.

[Skimmer]

^^^Ditto that!^^^

I've got those settings on my Fit (including the 1/16 toe out) and street manners have not been affected in the slightest. It does wander just a bit more on the highway in crosswinds and on grooved payment, but it's barely noticeable.

Just be sure and tell the shop to equalize camber as close as possible on both sides in the front. And make sure you/they simulate the driver's weight behind the wheel. In my homegrown alignment, this made a BIG difference in the camber readings.

[dj_oatmeal]

Ok so max camber as long as both sides are equal plus 0 to 1/16 toe out. What about caster? Can this be changed on the Fit? Thanks for the help.

[sl0wp0k3]

Originally Posted by dj_oatmeal

Ok so max camber as long as both sides are equal plus 0 to 1/16 toe out. What about caster? Can this be changed on the Fit? Thanks for the help.

no caster adjustment possible

[dj_oatmeal]

Well Honda let me down. Despite telling me they would be in the next morning the bolts are infact on backorder so will not be installed before the autox this weekend. The tires came in though and are very impressive even in the rain. I've not pushed them in the dry yet to be nice to them for the first hundered miles or so. Falken tech recommended 30PSI for the street but would not recommend a pressure for autox.

People on my local SCCA board are recommending around 45PSI to start and to make changes based on temp readings.

Does 45PSI for front 205 50 15 Azenis RT-615 sound right? Thanks.

[mahout]

Originally Posted by dj_oatmeal

Well Honda let me down. Despite telling me they would be in the next morning the bolts are infact on backorder so will not be installed before the autox this weekend. The tires came in though and are very impressive even in the rain. I've not pushed them in the dry yet to be nice to them for the first hundered miles or so. Falken tech recommended 30PSI for the street but would not recommend a pressure for autox.

People on my local SCCA board are recommending around 45PSI to start and to make changes based on temp readings.

Does 45PSI for front 205 50 15 Azenis RT-615 sound right? Thanks.

I'd start at the 40 to 45 psi range too and 35 to 40 rear. you do have front antisway bar right?

[dj_oatmeal]

Yes I have the stock front bar and the stock tires in the back.

[sl0wp0k3]

Originally Posted by dj_oatmeal

Yes I have the stock front bar and the stock tires in the back.

hah! that'll be fun...and slow. shoulda gotten azenis for the rears too.

actually i don't know...considering the amount of understeer i get w/ the crash bolts, that might actually be a good way to balance the car. but azenis will be wayyyy grippier than the stupid sp31's, which is why i think it's kinda stupid

[dj_oatmeal]

The back tires are hardly worn after 26K miles so I coulnd't justify replacing them yet. The back tires barely got hot at last month's event so I'm hoping that the large difference in front to rear grip will result in oversteer to get throught the corners quickly. If not then maybe you will be right and it will turn out to be stupid. I'm looking for a set of Saturn wheels and will get them setup for track use only with proper tires on all four corners.

[sl0wp0k3]

Originally Posted by dj_oatmeal

The back tires are hardly worn after 26K miles so I coulnd't justify replacing them yet. The back tires barely got hot at last month's event so I'm hoping that the large difference in front to rear grip will result in oversteer to get throught the corners quickly. If not then maybe you will be right and it will turn out to be stupid. I'm looking for a set of Saturn wheels and will get them setup for track use only with proper tires on all four corners.

do you not rotate your tires?

[dj_oatmeal]

No. Too many years of driving RWD BMWs being told not too I suppose. 25K out of 40K tires is acceptable to me.

[dj_oatmeal]

No. Too many years of driving RWD BMWs being told not to I suppose. 25K out of 40K tires is acceptable to me.

[Skimmer]

Your setup will be an interesting experiment with the SP31s in the rear. I think people who have tried smaller/harder compound race tires in the rear have found the car to be too lose in the rear. But Mr. Froge can tell you more about that. I believe that's his current setup. Your findings might be different with the Azenis, which aren't as sticky as R-compound auto-x tires.

[dj_oatmeal]

I'll let you know how it works out later this weekend. Hoping the front/rear mismatch will be what the car needs.

[dj_oatmeal]

Just what the doctor ordered. 41PSI in the Azenis out front and 40PSI in the stock SP31s in the rear. A quick stab at the brakes entering a corner and the back came around very nicely. Cut the gap between me and the front runners in half this time out. Last event I was 5.3 sec out of first this time I was about 2.3 sec behind first(results not posted yet for confirmation). My biggest issue now is the inside front tire constantly spinning as I exit the corner. Camber and rear shocks next. Thanks to all for the advice here. Video of a few of my runs YouTube - Honda Fit Orangeburg AutoX SCR-SCCA

[mahout]

Originally Posted by dj_oatmeal

Just what the doctor ordered. 41PSI in the Azenis out front and 40PSI in the stock SP31s in the rear. A quick stab at the brakes entering a corner and the back came around very nicely. Cut the gap between me and the front runners in half this time out. Last event I was 5.3 sec out of first this time I was about 2.3 sec behind first(results not posted yet for confirmation). My biggest issue now is the inside front tire constantly spinning as I exit the corner. Camber and rear shocks next. Thanks to all for the advice here. Video of a few of my runs YouTube - Honda Fit Orangeburg AutoX SCR-SCCA

I'll be a pest one last time. The reason the inside tire spins uselessly is because the weight transfer lifts the inside wheel via the antisway bar. As the outside suspension compresses, the antiswar bar 'lifts' the inside wheel much quicker than without the bar. If you disengage the bar the inside tire will have greater traction. And you will corner faster.
cheers and good luck.
PS what Orangeburg is that? SC? I lived in Sumter for a few tears and I see you're from Columbia.