i noticed something interesting today...after taking off my 17's with 215/45/17 nitto 450's with yokohava avs 100s in the rear and putting on my stock 15's with 195/60/15 michillen (asx or something?)tires that are worn out...it felt like the car was alot more stable and had more grip...i took a few familiar turns and was able to get on the gas faster without too much understeer where my 17's would understeer a little more and i would have to lift off the throttle to rotate the car...i was planning on ditching the 17's for some 16's or even 15's

This leads me to believe 2 things...either my 17's (which should corner better considering the tires i have) are unbalanced due to the mismatched tires i'm running or 215's(even though not be wide at all) aren't appropriate for my setup and the extra width(which should provide more traction) is providing a negative affect on cornering

with my current setup i have kyb agx with s/t frotn and rear swaybars...i'm thiking that even going with a 215 width tire on 16's might be too wide and going with a 205 would provide more traction with the way my car is setup?

so what do you guys think? is running a 215width tire hurting my cornering? i would like to say my car was understeering with the 17's because i had stickier tires in the back but i'm not sure..maybe i just can't drive

 

could be a function of less unsprung weight, but so far as i'm concerned the tire width should be ok @ 215. nitto 450's are terrible tires, and the es100's are grippier, so that could be why you couldn't get rotation on that turn you're talking about. (though you shouldn't really be "rotating" on the street anyway)

a quick point: understeer and rotation are two different things, though we all like to talk about them as though they're inverse of one another. Understeer is independent of rear tire grip, as it is simply a condition of the front tires losing grip. rotation is more like controlled oversteer, which is the opposite of understeer, yet not a function of negative understeer, to be mathematical. a more holistic consideration of a car's balance or handling characteristics would be the sum of both of these tendencies.

anyway, i've never heard of a 215 being TOO much tire for a 2400 lb + car.

 

nitto 450
worst friggin tires ever created
I speak from experience


15" wheels

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bad-monkey &raquo;</TD></TR><TR><TD CLASS="quote">
anyway, i've never heard of a 215 being TOO much tire for a 2400 lb + car. </TD></TR></TABLE>

we meet again...

I agree with what you're saying though

I think the reason you may be having problems with the 17" tires is that your suspension may be set up too hard for those tires. then again, they aren't good tires in the first place. you say 17" should be better for cornering...hypothetically yes, but are the rims heavier? 17" can have more load capacity, but not necessarily lead to better car "rotation" as you put it. anyways it doesn't matter if the tires suck.

you might have better luck with 205 tires, but then again you may not. I suspect your suspension is too stiff relative to the strength of the sidewalls on the tires. ideally you would soften up the front suspension a bit (if you really want to, put on stock springs and shocks - not swaybars - back to stock and then test both sets of tires) and stay with tires that have a stiff sidewall.

the rear tires aren't a factor by the way... not in this case anyways.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kablamo &raquo;</TD></TR><TR><TD CLASS="quote">

we meet again...

.</TD></TR></TABLE>

hehe, good day sir.

i think to fully diagnose what's going on we need more info. what car, suspension, etc.

 

it's a 97 accord ex coupe...i'm running hnr sport springs with kyb agx (set 3/4 in front and 7/8 in back) with s/t swaybars

i do notice that the sidewalls on the nittos seem a lil soft because i can feel the tires "squishing" around a little bit when i take ordinary turns..this was with correct psi also...

the stock rims with tires weigh about 2 pounds less than my 17's (38 vs. 40 lbs)..although i know the 17's would still have more weight towards the outside and all the affects of that...but i didn't know it would make an affect on cornering...acceleration and deceleration but not cornering..can someone explain why? is it because the momentum the wheels produce causes the car to be "pushed" forward causing understeer rather than turning?


i would test the car stock like kablamo said but it took me too long to put everything together (working by myself and slow worker = litlle progress) so i dun wanna do everything all over again lol

anyways..after driving around on 15's the car seems to drive much better than the 17's...i may end up buying 15's instead of 16's..i don't care if they'll look small on my car it's worth the performance

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dan GSR &raquo;</TD></TR><TR><TD CLASS="quote">nitto 450
worst friggin tires ever created
I speak from experience
</TD></TR></TABLE>

I second that

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by azian21485 &raquo;</TD></TR><TR><TD CLASS="quote">it's a 97 accord ex coupe...i'm running hnr sport springs with kyb agx (set 3/4 in front and 7/8 in back) with s/t swaybars

i do notice that the sidewalls on the nittos seem a lil soft because i can feel the tires "squishing" around a little bit when i take ordinary turns..this was with correct psi also...

the stock rims with tires weigh about 2 pounds less than my 17's (38 vs. 40 lbs)..although i know the 17's would still have more weight towards the outside and all the affects of that...but i didn't know it would make an affect on cornering...acceleration and deceleration but not cornering..can someone explain why? is it because the momentum the wheels produce causes the car to be "pushed" forward causing understeer rather than turning?


i would test the car stock like kablamo said but it took me too long to put everything together (working by myself and slow worker = litlle progress) so i dun wanna do everything all over again lol

anyways..after driving around on 15's the car seems to drive much better than the 17's...i may end up buying 15's instead of 16's..i don't care if they'll look small on my car it's worth the performance </TD></TR></TABLE>

moment of inertia with respect to wheels doesn't really affect cornering, in that the weight distribution within a wheel affects the car in a particular plane, (if forward is X, up down is Y, then the torque vector heads outwards to the side in the Z direction) though sidewall rigidity may have something to do with the profile of the tire, and power delivery (both braking and accelerating) to the wheels can affect entry/exits, input responses. but there's no direct correlation.

as far as your test is concerned, you'd have to spend alot of money to get it right new tires on the 15's, new tires on the 17's, same tire. Similar treadwidths, if not identical, and similar sidewall ht's. Then you'd want to rent out a skidpad, or find an empty lot and have some data acquisition. Either a G-meter, or an accurate way of recording your velocity, and bla bla bla.

15's are great, i love mine. but a word of caution is that for heavier cars, sometimes it's hard to find the right tires in the right widths. aka, the only size falken makes azenis in for a 15" rim is 205/50/15. Which isn't that important for the daily driver, but from a street tire competition (aka auto-x) perspective, can be a little debilitating on your performance or your wallet. Upsizing to a 225/50/15 can be expensive (BFG T/A KD @ 135/tire). IF you're in a R-compound class, 15's are better since most tiremakers make a variety of 15" r-comps, and it costs alot less that it woudl for 17's or 16's.

 

hey how wide are your tires? also, do you run the 15's daily driven or just on track days?

 

the weight of the rims/tires being at the inside or outside doesn't actually affect cornering, just acceleration and braking. however bigger/smaller rims usually have different combinations of tread width, contact patches and sidewall stiffness, which is what alters the handling performance. That's why it's hard to directly compare your 15's to your 17's because they have different tires, different sizes, different profiles...

There is a general perception out there, mostly influenced by the desire for cosmetics, that bigger rims (even within reason) are always better. not always so... I think your car may be good with 16's, but then again like bad-monkey says 15" rims with really good R-compound tires will probably outhandle 16" rims with any conventional street tires.

Anyways, it really depends what you want out of the car, and what you are planning on doing with it. for auto-x i say you stick with 15's, but if this is just a daily driver where you want good performance, you might want 16's.

i'm guessing you have a 4th gen lude (only gen that came with 15" stock), keep in mind that the farther away you get from stock dimensions, the more work you have to do in terms of engineering which parts you should install.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by azian21485 &raquo;</TD></TR><TR><TD CLASS="quote">hey how wide are your tires? also, do you run the 15's daily driven or just on track days?</TD></TR></TABLE>

205/50/15 on the a/x wheels, 205/50/16 on the OE wheels. my next set of tires will be either 225/50/15 or 245/35/17 () on the a/x wheels and 215/45/16 on the OE wheels.

 

Basically, when you switched tires (215 to the 195's) you provided less grip to the rear of the car. Which is causing the rear to rotate more (less understeer -or- more oversteer however you want to look at it).

It is just another way to setup your car. Some people w/ FWD vechicles like to use larger sway bars on the rear of a car to induce more oversteer (or less understeer), others do it with less tire grip in the rear (what you did)... they are all a means to the same end ---&gt; less grip for the rear of the car.

Do I think you should run different brand/model tires front to rear? Not really, I would at least suggest the same brand/model of tire so the characteristics are similar, just change the tire width if you want to go this route.

BTW - I run different tire from to rear on my Prelude for autocross... 215/45/16 Front and 205/50/15 Rear. I don't need to spend money on a larger/heavier rear sway bar, the tires are cheaper and lighter, and the wheels are cheaper and lighter.... win, win, win, and the same end result...