this is for autocross..it's something i was thinking about...i was playing with the idea of running staggered 16x7.5 215/45/16 azenis front with 15x7 or 6.5 205/50/15's rear...i can get the 15's for pretty cheap..but they'd be heavier than the 16's..how much does rotational mass affect the rear wheels?

well i know rotating mass will have an effect on cornering, acceleration, and braking...especially on the front wheels (since rear's don't do anything)

but, having the wheels on a "dead" part of the car would it effect it as much as if the heavy rims were in front? i suppose not..

here's a scenario..suppose i'm running equal front and rear rates instead of higher rear (10kg f and 10kg r):

my theory is this, by running the staggered sizes, i'll get better turn in from wider rims and tires up front (very slightly less profile as well) and the high spring rates..(as opposed to having a 8kg f and 10kg r setup for example)

in the rear, i'll be able to dial in better oversteer because of more narrow tires and rims, and heavier mass in the back

problem is, the 215's are a little over half an inch larger in diameter than the 205's...is this a significant difference? Also, will this type of setup cause my rear end to be too loose and unstable during transitions and stuff?

i saw a thread earlier about how japanese tuners run staggered sizes to induce oversteer (but with high front biased )spring rates and here in the states people get oversteer from high rear spring rates...wouldn't this idea be a happy medium then?

sum it up:

10kg front and rear
16x7.5 215/45/16 front
15x 7 205/50/15 rear
rear swaybar?

only reason i thought of this was because the azenis don't come in good sizes for 15's and next best thing were the 215/45/16...but i guess they supposedly are supposed to have better sizes in 15's but who knows

 

I don't see it being worthwhile on anything under 2300 lbs or so.

 

Well my idiot verse says it's simple

The tires are the only part that touch the ground so in tuning handling start there

There have been lots of threads about this and most of them end up with a so called FF whiz telling you it's a bad idea and you should copy his last years set up

I personally think very highly of this and use it my self, if you read the ricer trash I'm sure you've seen the article on the raceline integra moping up in it's class on staggered sizing and of course quite a few japanese tuners and racers use it even those with ties dirrectly to Honda R&D

There is however a more practical and simple way to think about it

With rolled fenedrs I can run a 205 in the rear but a 225 in the front so why give up tread width to run a narrower tire in the front ?

It's not hard to imagine that a vehicle expericing understeer can correct this in some part by running narrower tires in the rear and vice versa for oversteer

 

Well in STS this year Kevin Mccormick, ran 205/50/15's but ran 7.5 wheels up front and 7 inches in the rear...

 

i plan on experimenting extensively with this next year.

i tried running a friends 205/50/15s on the front and my 195/50/15s on the rear of my turbo d at a recent autox.

i liked the way the car drove more with this set-up than running my 13x8s and hoosiers all around.

i just dont see the reasoning behind starting out with equal grip at both ends, then taking grip away from one end with suspension tuning. makes much more sense to me to just start out with less grip on the end you want to slide first

 

This is true. I like the staggered setup on a fundamental level. However, for THIS TIRE in THOSE SIZES, I think it's pointless. I've decided against it for my own car. Now, if something significantly wider (more than .4" of treadwidth) than the 205 Azenis came along in 16", that'd be another thing, but right now it's a much better idea to wait and see what's available in the new style Azenis in my opinion.

 

I've been wondering about this too. All too often I hear the phrase "the rear is just along for the ride" in a FWD car. So that makes me think about why we even want to put sticky tires in the rear? The only way that I can rationalize it is that if you maximize grip in front and in back, your maximum traction level will be greater than if you had a really stick front and a not-sticky rear?????

 

I'm run that exact 215F/205R setup on my Prelude with success. It induced more oversteer without having to stiffen the rear of the car, which allows the car to have more feel. Too bad there is no where for the car to compete...

 

well, if they made a 245/35-16, or 245/40-16 in a A compound i would be all over those for the front on a 10" wheel, and still keep my 205/50-15 in the back on a 7".