I definitely wouldn't mind a ranking of the feedback and sharpness levels between the stock Dunlops, the FK452s, and the 245 RT615s.

 

Steering response eh well lets consider this;

225/45/18 sidewall is 45% of 225= 101.25
245/40/18 sidewall is 40% of 245= 98.00
245/35/18 sidewall is 35% of 245= 85.75

now IMHO the whole reason your getting "better" feedback is because the 225 is being streched over the rim more and there is less sag in the sidewalls, and therefore less flex. Now the smaller you get your sidewall the better this feedback will get, i think if you went with a 245/35 vs. a 225/45 you would get better feedback with the 245 and more grip.

However to me steering response is not key, finding that middle ground where a marriage exists between the sidewall not folding and the max of grip is key, this is where you'll find the "best" handling.

I suggest GoodYear Eagle F1 GSD3s if you want a streetable tire thats going to last a while with very competitve preformance, RT-615 if you want near the best performance and can afford a new set every 20,000, and the Advan Neova or BridgeStone Re01r if you have the money and can drive the car at the peek of performance (i.e. track)

 

You're saying that the shorter sidewall yields more feedback, yet 245/40/18 is shorter, yet ZoomZoomH encountered less feedback with that combination.

I don't think that these calculations are relevant. Consider a 255/40/18 tire, which would yield 102 for sidewall height. Yet the arguments so far say that a 255 width would cause more roll, so it's not because of the height of the sidewall.

Is it because of the "shape" of the sidewall in relation to the tire width? The stock bridgestones/dunlops cave in below the rim, so the sidewall is diagonally positioned, slanted towards the middle of the tire. So perhaps when a lateral force is applied, and the tread pushes against a sidewall, it ends having to more against the rim (i.e. the force is spread more vertically).

*shrugs*

Since the tire sidewall construction is different, and there are many different factors between different tires, I'm really more interested in the experiential "feel" from particular combinations.

 

Sadly this is why tires is so much a black art. Different tires also like different pressure settings and different temperature ranges. Tuning tires is just as important as the right tire selection. I would not more concert information, but for now we can only rely on feedback. I'm surprised at the report that the 245 Azenis felt so soft though, it seems that other people have reported that the Azenis are very stiff.

 

I accounted for ZoomZoomH's findings with this sentance:
"now IMHO the whole reason your getting "better" feedback is because the 225 is being streched over the rim more and there is less sag in the sidewalls"

Even if the calculation says your sidewall is going to be smaller your still streching a 245 over an 8'' rim vs streching a 225 over an 8'' rim.
You're going to have more sidewall sag even if the sidewall calculation says your going to have a smaller sidewall.

All i'm saying is comparing a 245/35 vs 245/40 vs 225/45 the MUCH smaller sidewall on the 245/35 is going to provide a shaper steering response then a 245/40 making it probably really close to the feel of a 225/45.

However like I said streering response isn't everything.

 

oh the 245 azenis is not soft at all, if it wasn't for the super-stiff sidewalls i'd probably gone back to 225's much earlier than just now lol

it is all subjective at this point IMO, just go ahead and get the 245's and see how it feels for you, i've done it and have determined what I like better on the stock rims, experiment people, experiment!

*insert obligatory YMMV notice, lol*

 

If I get the Azenis, I'll probably get the 235/40 anyway. The RT615 235/40s are unusually tall and so the speedo difference between that and the 245/40s are minimal. I'll try to contact Falken to confirm that they are indeed that height.

 

Shouldn't the 235s be shorter than the 245s? Falken makes the 235s taller than what the #s say? Maybe I'm not reading your response right...

FS

 

The 235/40 that Falken makes is quite fall for a tire of that size, but still very slightly shorter than the 245/40.

 

Wow, that's why it's soo hard to pick tires, isn't that right LionZoo? In mt case i'm going with 245/45 RE-01's. Hopefully I will get them mounted this Saturday. I'll keep you guys updated if you'd like.

 

That would be nice. Initial impressions are good, and impressions are break in are nice too. You have the RE040s correct?

 

The manufacturers width isnt a precise measurement. I had 255/40/18 RT615's and the actual measured width of them was within mm of the 245/40/18 toyo R888's that replaced them.

 

Right, but you're comparing between two different brands. Within the same brand and the same model, the listed dimensions are a fair guide for comparison purposes.

 

Correct, I guess I was just pointing out the fact the 245 isnt always (in fact rarely is) 245 as most think. So grip levels from one 245 will be different because of both compund AND width being different.

 

Interesting, thanks. I am very slightly concerned with the height as that's the thing affecting the speedo. But, I think I have made up my mind and I'm going with the 245/40/18 RT615.

FS

 

good choice, wasn't exactly what I was looking for but may be the perfect setup for you, good luck with it

 

The 235/40 is 25.5 tall according to Falken while the 245/40 is 25.6 tall. That's a 0.1 inch difference, 0.2 at most if you take into account rounding error. The height difference is only a couple tenths of a percent while the 235 is 2-3 pounds lighter depending on which literature you believe and possibly a better width for the wheel.

 

225 front and 245 or 255 on back. Thats what im doing.

 

You do realize you will upset the neutral handling characteristic of the 8, right?

FS