Car Analogy

This is exactly the thinking process my conclusions are aimed at, those 'trusting' Honda engineers research, and going with their 'recommendation'. I am in that camp, not really interested in making lots of mods, I'm running stock wheels, etc.

My point of the reasearch and conclusion is the tire size choice Honda made for the CR is not really 215/255. Its really 215/245 (actual tire dimensions). The RE070's are virtually the same size as most any other 245, and most other 255's are much wider than the RE070 255.

So if choosing tires with dimensions similar to what the CR was equipped with stock is your goal, you really ought to be choosing 215/245.

s2000Junky

Keep in mind though that the CR 255 narrower as it may be, still should be larger overall from 24.7" to 25" as typical (check to verify on the RE070) This will influence gearing a small amount, as well as breaking bias and handling feel overall. Lateral grip is only one part of the equation, and yet that can be effected as much or more by tire compound choice when your only talking 10mm width difference otherwise. If your a purest, its going to be challenging to stick with OEM tires eventually so some small compromises may have to be made in staying 100% integral to how the CR handled leaving the show room.

alSpeed2k

Thanks, SlowTeg, It seems like we will have similar setup (no aero, unless lip spoiler counts :P, default Ohlin springs are 10.2k/8.18k). Maybe I should look for a '00/'01 or CR bar to try first.

Bullwings

The CR bar is perfect. It's just enough to balance things out at low speed; however, at speeds greater than 95mph, I do feel a little bit of float, but I think that has more to do with the aero of the car itself and my own skill set as a driver. I tried a 255 square setup with 9"/10" F/R wheel width stagger and didn't care for it. It didn't provide that much extra stability at higher speeds, and it also pushed too much for my liking at lower speeds.

So far, the best setup for me has been a smallish wing (GTC-200), CR bar, square 255 wheel/tire, 700F/600R springs. It maintains low speed playfulness to get the quick rotation that I want for tighter low speed turns, and at higher speed the wing balances out to give me the stability and confidence that I need to push harder and keep my foot planted.

Keep in mind that my setup is optimized for track use. If I were to do more auto-x, I'd probably look for a larger/stiffer front bar to improve repeated left-right-left-right transition response and speed.

SlowTeg

I don't have a wing yet but I definitely agree. At some point I will add a wing, and it'll help with higher speed turns. Compared to cars with a rear wing (also on a square setup), some friends are able to stay flat out on some higher speed turns whereas I have to ease up a little because the rear gets a little light. At lower speeds a wing won't affect the handling, but it helps on higher speed stuff when the poor aero of the car shows.

rpg51

Lets say you own a stock 02 ap1 but you are running 17" ap3 wheels. What size tires for 100% street somewhat spirited driving on weekends in summer? How will the choices affect handling at street speeds on good winding roads?

Car Analogy

Stock sizes on stock wheels is always a good place to start. If you upsize both front and rear, you mostly maintain the same balance front to rear as the stock sizes, but with a little extra grip.

If you upsize just the front, or just the rear, you alter the balance, and will either give you less understeer, or less oversteer, depending on which end you upsize.

Running upsized tires will result in a slightly pinched tire. So its not without some side effects.

Unless you have a specific goal you are trying to achieve, I wouldn't stray from the stock sizes on srock wheels, except as mentioned in previous posts, I wouldn't suggest CR size rear.

rpg51

This is all a bit confusing to me. Others have suggested that the advantage of significantly increased tire selection and, (they say), slightly improved handling, is a reason to run ap2 wheels and ap2 tires (215 and 245) on an ap1. I did not understand that there was a downside to that modification. I take it you see it differently?

Chuck S

A buddy with an '02 reported nicer overall handling when going to 17" wheels (AP2V1). And a year later nicer overall handling returning to the OEM suspension from the lowered setup on the car when he bought it. Certainly a sample of one (1).

I was curious when I started this thread about potential handling on my '06. I went to the 255mm Bridgestone S-04 rear tires and don't feel any difference from the 245mm RE-11A tires I just took off. I suspect tire selection has the greatest effect and that 10mm makes little difference either way. Another car at the Gettysburg get together just fitted the same tires and I heard no negative comments. I'd expect a 30mm difference in front (245 vs 215) will be more noticeable than 10mm in the rear.

-- Chuck

Car Analogy

That is not what I am saying at all. I am saying to run tire sizes that fit the wheels you are using. The tires the wheel was designed to use. You can get away with going with a wider tire than stock for that wheel, but the downside is the tire will be a little pinched.

If you have a specific goal, like you want to quell an existing oversteer issue, and you don't want to do it right with suspension changes (different spring rates, sway bars, etc), then you can have some impact by upsizing just the rear tires (at the expense of some pinch). Likewise upsizing front only would have the effect of reducing understeer.

Note I am talking about you have a set of wheels you want to use (in your example ap2 wheels on an ap1), and do you run the stock sizes for that wheel vs upsizing one size wider than stock for that wheel.

I understood this was what you were asking. If you were asking what would be the impact of running ap2 wheels vs ap1 wheels (with their respective stock size tires for each wheel), than that is a different question.