I know this should be searched, but I need some opinions and info that I don't expect to be able to find. If someone can help me out, I'd greatly appreciate it. So here goes:

I want to run a 16x8" enkei RPF1... my main question is that they only offer it in a +38mm offset for a 4x100 bolt wheel. Will I be able to run those wheels without rubbing, or will I need to do some sort of fender flares? I assume rolling the fenders will need to happen, since I'd probably run a 265 or maybe just 255mm wide tire on them.

Just for reference, I'm mainly into autocross/road racing, but it also needs to be a streetable car. I don't want to run something ridiculous like 4* of camber, just because I don't want to go through tires every 5-10k miles.

I'm trying to decide between these 16x8's or a 15x7 setup.

 

Huh? A 255 or 265 tire is WAY too big for a '97-00 Civic. On 16" wheels, you need to get either 205/45-16 or 215/45-16. And 16x8 is too wide for 205/45-16; you'll need to go no wider than 16x7.5.

 

I found this picture and saved it a while ago. this is the biggest you will be able to fit under the wheel well.

 

As the guy below you posted, you can run 225's on a 15x8 just fine. I was well aware of that. Backspacing plays a factor, as does camber...but I was just curious if anyone has done it. I'm trying to be more competitive in my local autocross region, and I don't want to spend the money on new tires if they aren't an upgrade.

And I'm not going with a wide wheel just to stretch the tire, I want a wider wheel to put more rubber down. Better traction when I get my swap done, as well as better low-speed cornering for the auto-x.

And in reference to the picture posted, that guy looks like he's running almost 0 camber, maybe 1*...I'd bet a 245mm tire would fit OK running about 2.5* of camber. edit - and not on a small offset either. I was wanting more like a 40 offset to bring the wheels in just a little bit. And ride height also affects things when you have the right camber setup.

 

Another thing you need to take in consideration is the trailing arm. Make sure the tires do not rub on it or wheel spacers will be needed.

 

A wider wheel and/or a wider tire doesn't "put more rubber down". The amount of rubber on the road, which is called the area of the contact patch, depends only on the pressure in the tires and the weight of the car, and not on the width of the tires or wheels. If you have a 2640-pound Integra and you inflate the tires to 33 pounds per square inch, the area of the contact patch is going to equal 2640/33 = 80 square inches, regardless of whether you get skinny 175 treadwidth tires or 245 steamrollers. With wider wheels and tires, the shape of the contact patches will differ - wider side to side, shorter front to rear - but the size of the contact patches will be exactly the same.

 

i'm not sure how similar integras are to ek's but i test fitted a 16x8 +38 rpf1 on my teg and the front and rear were pretty close to the knuckle and trailing arm. i'm not sure how much lower on the offset you can go, but i would definitely have to roll the rear fenders, maybe not too much on the fronts (depending on tire size).

 

That is one of the most stupid afirmations one can ever made, please get this guy a phisics book. Please take a look to tirerack or some page where the width of a tire is described. As the size of the tire increases (175 - 195 -205 -225 etc.) so does the section width which is the one in contact with the road. (http://www.tirerack.com/tires/tirete...jsp?techid=200)
And about the relation between the weight of the car and the psi of the tires, you gotta be really dumb to consider that. Pressure does change at some extent the amount of rubber but just in a small percentage of your tires section width. You cant have a huge contact patch just by deflating your tires, please!

 

This is debatable. Technically its not the section width thats in contact with the road. Thats just the measurement of the overall width of the tire. The measurement of the tire that contacts the road is contact patch. That will vary depending on car weight (load), pressure, tire design, alignment, etc. Im not sure if you meant 'you can't have a huge contact patch by deflating your tires' or you can. But its true that you can, however this is mostly for drag racing.

Another thing to remember is that the wider the contact patch is, the shallower it is. This can be good for lateral grip, but tends to break away very quickly as opposed to a longer patch that breaks away more gradually. Also the wider contact patch has the possibility to curl up under load, which actually reduces grip.

Overall, the choice should be to use the correct size tire for the car, in the stickiest compound you can find for the intended use. Then if you need more grip, you can go with wider tires to a point, then it starts to get counterproductive as weight increases, and suspension geometry is drastically changed.