Hi guys,
Has any you tried 225 50 15 with 15X7 rims? I thought it would be tight.. I put them on last night and they were way over "tight" With the lowered height of the car, it would rub... even if I rase it by one centimeter, the chances of rubbing is still high... What to do What to do? besides getting 205 tires...
thanks
Jack

 

werd

 

I run 225s on my car and it's lowered about an inch. I use 43mm offset wheels and I had to roll the lip on the rear. If you're using 38mm offset you'll have more rubbing problems even with rolled lips. I had rubbing even at stock height with stock springs. 43s will also rub a little on the trailing arm, but not in a bad way.

 

I will be trying 225-45's very soon.

My car wont be at "stock" ride height, but I'm in the process of raising it.

I agree, I have driven my car and a stock ITR in the same weekend on the track, and the stock car feels awesome!

Bryan

 

????
Regardless of tire size, I lowered my car about an inch --- because of track use. Not for looks.

 

My car is higher than stock, mostly to keep 225/45 Hoosiers from destroying themselves or the rear bumper.

The difference in ride height (performance wise) is negligible.

Warren

 

Umm...do you have numbers to back this up with? All of the "professional" Integras that I've seen racing have been lowered (with a little fenderwork massage), so there must be something to it.

There is no such thing as having the CG too low.

 

Tell me about it.

Hoosier AS303 + no mud flaps = paint remover

I figure by the end of the season I'll have no paint on my front doors or rear bumper.

 

And I bet those Integras have non-stock suspension geometry, and bump steer kits. There's nothing wrong with lowering the CG, but you can't throw suspension geometry out the window. Also the lower you go, the more your car wants to lean, and the spring rates just go up and up. It's a vicious cycle

Warren

 

Just make sure the spring rates are high enough so that they won't bounce off the bump stop.

 

You're statement is debatable. As Warren pointed out, the roll center changes at a rate greater than the cg of the car when changing ride heigh. So when lowering the car, spring rates have to go up just to maintain the same roll stiffness. It gets worse the lower the car gets, to the point of having a ridiculously high spring rate to keep the same level of roll stiffness of the stock car on a seriously lowered one.

 

Not quite sure of what you're trying to say, but you made it sound more complicated than it really is. When CG is lowered, the moment arm (distance between CG and ground) is shortened --- thus less roll. That's it.

[edit] after re-reading the replies, I guess there're something in the suspension geometry that I'm not aware of. Please advice why the control arms would behave differently when lowered.[/edit]

In addition, lowering the car provides better air profile.

Disadvantage of lowering a car is, when brake into a turn (or clip the strip at apex or track-out), the car is more likely to bounce off the bump stop if springs are too soft. And with F20K (1120#) springs, you can basically eliminate that even with the wheels tuck under the fender. F20K is not "ridiculously high" for a race car.


[Modified by Wai, 1:24 PM 4/8/2002]

 

I wasn't saying that a car scraping the ground is always better than a car that isn't. But from a simple standpoint of Physics and racing, a lower CG is always going to be better. Now, suspension geometry, springrates, shocks, camber, etc are going to play into how low you can go and still have a good car, but we aren't arguing that point AFAIK.

 

My recollection of the tables I posted long ago is that vertical roll center displacement at both ends is near 1:1 with respect to vertical displacement of the respective ends of the car. So no significant increase in roll moment within the range of sensible lowering. Front and rear roll centers are very close to the ground, and they will pass thru the ground plane (if that's something that concerns you).

You can run 225's with 15X7 43-45 offset. You have to roll your rear fender lips and run spacers - and it will be tight but ok. The bigger problem is that while you will get more grip from the 225's you'll lose a little response (225's would be happier on an 8 inch rim - and would show it by being crisper in transitions).

Scott, who thinks most people should keep life simpler and run 205's.....

 

Will

 

oh gawd.... do I need a freaking PhD to understand all that??
Is there any simpler explanation of why lowering a car is "not necessary"? seems like couple of you here are saying that.

 

It is not necessary to lower the car in the sence that the ITR is very well balance stock. The problem with lowering the car in the "common" sence is that most people don't concider the balance of the car and just change for shorter springs without compensating the rest of the set-up. A bad set-up can give you a lost in handling, a lost in stoping performance (bad weight transfer back to front ) and even a lost in acceleration performance. I think comparing whatever you are going to do with what Realtime Racing does with several ten of thousand $ of budget for testing is not wise. Unless you have a racing team with big budget, I would try to improve handling using more simple and less "complicated" methods (bigger sway bars, rear upper strut bar, different tires combinations...).

 

The simplest explanation is first-hand experience. Take your stock ITR out on the track and see just how great the stock suspension is.

 

It all depends on the driving preference. It works fine for person A might not work as well for person B.
After several (well should say numerous) rides and drives on different ITRs with different suspension setups, I set my car up ground to fender lip at 595mm front and 600 rear, of course that has to go along with all the specific things on my car like tire size, spring rates, alignment, etc.

 

Wai,

I think you misunderstood my post. I'm not arguing that the ITR suspension can't be improved upon, rather I'm saying that before you touch anything, learn to drive on the stock suspension. This way you can make changes to the suspension that fit in well with your driving style.

 

205s are best

 

Seriously. When people ask about coming out to the track the first thing they usually say is "yeah, I'd come, but I have to do my suspension first", which usually means a 2" drop with lowering springs on stock shocks.

 

I have a friend with a 95 M3 and it handles beautifully! The ride is pretty darn stiff for stock. I hear that the new M3 is even worse - so bad that some people are swapping out the springs for lower spring rates. Unfortunately I haven't had the opportunity to experience the new M3 for myself <grin>.

 

The ride is fine, those people are pansies!

 

Yeah really. They asked for an even better M3 and got it, and now complain about the way that the diff is noisy and that the ride is too harsh. If I had an M3 I'm sure I wouldn't give a damn about the harshness of the ride. The same goes for a GT2, if I could ever get my hands on one.