dreamshadow - You need to decide what class you want to run in and then make your decisions based upon the rules. Get a rule book first and attend some local autocrosses. Talk to some of the experienced drivers. Most of them are willing to help with advice.

 

I haven't mess with autocross set-up's in a while since I dumped my CRX YEARS ago...

For the most part, running 225/50/16 tires should not be a problem.

You could run into a problem getting the tires hot enough if your course is very short (30 seconds or so) with very cold ambients.

The tire pyrometer will definitely confirm if the tires are getting up to temp.

The FC chassis can be dropped down to 2700# range with driver, and this might not heat up the 225's on a very short course with low ambients (under 60F)...


-Ted

 

I thought the reason that you look at tire temps is for the inner, middle, and outer portion to make sure that your suspension is set up right?

JAmes

 

hey guys, i got the vert rims now. i have 205/50/15's on it, does that still count for stock size? or am i in a different class now? i havent autocrossed yet, or been able to drive my fc too much too, i'm used to cornering with fwd's too...=\ . well, once i get my alignment done, then i'll be driving it more. hey was does car weight have to do with tire temp? shouldnt the change in temp of tires affect the car regardless of weight?

 

Tire dimensions don't matter. It's the rim dimensions. If your car originally came with 14x6 then anything other than 14x6 will bump you out of stock (assuming other mods haven't done that already).
Part of the tire heating is from the tread/sidewall deflection... which is related to the weight of your vehicle. If your tire is too wide, and your car too light it will take a long time for the tire to get up to temp. Conversely, if your car is heavy, and the tire too narrow the tire will become over heated, the grip will fall off, and you'll start tearing the tire up.
I don't think a mostly stock FC is going to be anywhere near the "too light" end of the spectrum on normal tires. RETed is right about ambient temps being a factor though.
I'm building an FC to be 1900lbs and it will run on a 10" wide tire and I'm not worried about the tires getting up to temp... but then again I'm in Texas. I've measured surface temps @ 140F in July.

 

ooooh, ic....
hey another question, my car is lowered, so i have too much camber, i can see it. well, i went to a shop today, and they said they only align to factory spec. i wanted to have .4 in the front and .2 in the back..... what is factory spec? is it much different? will it be bad with a lowered car? and i heard factory spec had a lot of understeer, which is what i want to get rid of of course...

 

Unless you have camber plates up front and an adjustable camber rod in the rear, you cannont adjust the camber on your car. The stock suspension only had adjustments for toe both in the front and rear.

- Cooper Lacy