So, we're nearly a quarter century out from the S2000's introduction, and the OEM 16" tires haven't been available for years -- sounds like the perfect time to analyze them!
First, a reminder of what's long been known (and in fact was stickied at the top of the Wheels & Tires subforum back in 2002): the official tire sizes for the OE 16" rims were misleading, and are a big part of why the original AP1 had such a bad reputation.
In this post, I'll try to quantify how much "wider" the rear 16" tires *effectively* were, in terms of the amount of rubber available to put on the road. (To my knowledge no one else has actually tried to do this.)
Let's start with a look at the tires. Here's a photo of a new front/rear pair of the OEM Bridgestone Potenza S02s. (Front at left, rear at right.)
[Note: Image created from photos originally posted by @s2ka .]
Recall that while the Potenza S02 was a widely available line of tires, Bridgestone actually worked with Honda to develop the S2000's tires specifically for the car.
Now, the front tire was officially a 205/55R16 tire (205mm section width, 55% sidewall, 16" rim), and the rear was officially a 225/50R16 tire. Therefore we'd assume the rear tire was nominally 20mm (9.8%) wider than the front. The problem is this wasn't even close to being true. To see the real difference, let's digitally duplicate each tire and compare the two pairs:
And just to drive the point home, here's what they look like stacked flat against each other:
Folks, that's a lot more than 10% difference -- in fact, it's actually about a 15.3% "width advantage" for the rears! Again, this is not a photo editing trick: those of us who ordered new sets of these tires from Tire Rack can remember that they really did look like that when stacked side by side.
But that's just the beginning; there are two other *big* differences.
First, notice how rounded the edges of the front tires are, and how square the shoulders of the rear tire are. This means that the rear tire actually puts a bigger *percentage* of its section width on the ground than the front tire. So even if they were the same width, the rears would still effectively be "wider" just because of its shape! How much wider? This is harder to quantify, but let's conservatively call it a 5% "shoulder advantage".
Finally, notice how wide the tread *gaps* are on the front tire, and how narrow the gaps are on the rear tire. This means that a bigger percentage of the rear tire's contact "patch" is actually touching the ground. So even if the front tires were the same width *and* the same shape, the rears would STILL put more "rubber on the road". I actually tried to quantify this by processing the tread images so that the rubber was pure white and the gaps were pure black. Then I simply measured the percentage of each tread pattern that was pure white. Here's what I found:
In the left side of the image, we see that over 78% of the rear tire's contact patch is actually rubber; but for the front tire, the percentage is less than 72%! That's a "tread pattern advantage" of about 9% for the rear tire!
So let's put all this together: The total "grip advantage" of the S02 rear is the product of all of its advantages: grip advantage = raw width adv. * shoulder shape adv. * tread pattern adv ~= 1.15 * 1.05 * 1.09 ~= 1.32. So the rear S02 actually put down a little over 30 percent more rubber than the front!
So if the tire specs were made to reflect the actual difference in "rubber on the road", what would the AP1 stagger actually be? Well, as krazik points out in the link above, the rear tire would be rated as 245/45R16; therefore if the fronts are ~32% narrower, that's equivalent to a 185/60R16 front tire -- in other words, the tires actually have a whopping 60mm of "effective stagger"!
OK, fine, but the suspension was designed to accommodate the difference, so where's the danger? Well, there were plenty of owners who replaced those S02s with all-season tires, snow tires, or just a different brand of performance tire -- but of course they used Honda's specs, and bought "regular" 205 fronts and 225 rears. Suddenly the rear of the car had *far* less grip relative to the front -- with predictable results.
Finally, there's one more bit of danger inherent in the rear S02s: that narrow tread gap only got narrower as the tire wore down (and Honda advised owners it could wear in as little as 10K miles!). Here's a photo of a new one vs. a worn one:
That worn tire was fine in the dry, but it was a genuine handful in the wet. I vividly recall a white-knuckle highway drive on worn rear S02s in a rainstorm: I was hydroplaning at 45-50mph, while traffic around me passed serenely by at 70+.
The moral of this (too-long) story: if you still drive an AP1 on the OEM 16" rims, follow krazik's advice and at least get a 245 tire for the rear. You can also go narrower than 205 at the front (if you can find it), but the wider-than-spec rear tire is absolutely essential. But even if you're just interested in handling, it's good to know what F/R grip ratio the original suspension design was based on.
Stay safe out there!
Edit: P.S. I posted this here in the Suspension forum (rather than Wheels & Tires) for a couple reasons: this post is more about the effect of the tires on handling, rather than simple tire fitment (which the wheels forum is usually more concerned with); also the Wheels forum already has krazik's sticky post about getting 245 rears.
Edit 2: Lol as Doc Hudson said, I guess my mind's been changed for me!
I noticed a similar, but reverse, concern with the stock CR rear tires. The oem rear tire spec is 255, leading some to try and emulate that and spec 255 rear for their ap2.
The RE070 oem 255 rear chosen for the CR is actually much closer in dimensions to what any other tires size 245 would be.
The RE070 chosen for the CR didn't come in a 245 size. So Honda chose the closest size it was available, 255.
The problem is if you foloow that spec, for an actual CR, or an ap2 trying to copy CR, most any other tires 255 size will be significantly larger than CR came with stock.
Choosing 245/215 with most tire is actually very close to dimensions that came stock on CR.
On another note, the ap2 has a narrower stagger gap, but also has much less rear bias.
It seems Honda wanted to go with a more modern wheel size for tbe time, 17". They also wanted to ditch the toe changes with suspension travel designed into ap1.
The way they decided to go appears to be reduce suspension bias, along with removing designed rear bump steer, which allowed reducing the stagger gap.
If you fit ap2 wheels to your ap1, you still need the wider ap1 stagger gap, as you still have built in bump steer (unless you change to ap2 rear subframe), and the rear suspension rate bias (unless you switched to coilovers - note, lowering springs all have similar rear bias as stock ap1 rates).
So ap1 you probably should use CR 255/215 specs to have larger stagger gap. But for ap2 and CR, personally recommend use 245/215.
Thanks for posting this especially the photos of the tread pattern of the original Bridgestone S02 tires.
Been running 215F/255R Bridgestone S04 tires on my 2006 car.for the past seven (7) years without any drama. (Just saying.) The tires are pretty much aged out and finding 255 rears in a Max summer tire is very limited. Extreme summer tires are usually loud but 255 are pretty common.
At first I was like what the hell is this post about? They designed it with a certain handling characteristic tuned for driving feel not all out grip, etc. but this post was super informative.
basically if you went with the stock tires you’re good, but if you go aftermarket you need to understand how much stagger is required for the balance they intended. A problem everyone has as tires are phased out.
This makes you think that the stagger of the 17" wheels with the 215 front and 245 back are the same (or very close) as with the orignal 16" Potenza S02 ones.
^Correct. In fact I believe the 17" setups actually have less "effective stagger", since the 215 and 245 RE050s have widths that are "true to spec", and their tread patterns and shoulder shapes are comparable. In other words there's no need to worry about a radical change in handling balance when replacing the RE050s with other brands/models (assuming the replacements are also "true to spec" of course!).
So, we're nearly a quarter century out from the S2000's introduction, and the OEM 16" tires haven't been available for years -- sounds like the perfect time to analyze them!
First, a reminder of what's long been known (and in fact was stickied at the top of the Wheels & Tires subforum back in 2002): the official tire sizes for the OE 16" rims were misleading, and are a big part of why the original AP1 had such a bad reputation.
In this post, I'll try to quantify how much "wider" the rear 16" tires *effectively* were, in terms of the amount of rubber available to put on the road. (To my knowledge no one else has actually tried to do this.)
Let's start with a look at the tires. Here's a photo of a new front/rear pair of the OEM Bridgestone Potenza S02s. (Front at left, rear at right.)
Recall that while the Potenza S02 was a widely available line of tires, Bridgestone actually worked with Honda to develop the S2000's tires specifically for the car.
Now, the front tire was officially a 205/55R16 tire (205mm section width, 55% sidewall, 16" rim), and the rear was officially a 225/50R16 tire. Therefore we'd assume the rear tire was nominally 20mm (9.8%) wider than the front. The problem is this wasn't even close to being true. To see the real difference, let's digitally duplicate each tire and compare the two pairs:
And just to drive the point home, here's what they look like stacked flat against each other:
Folks, that's a lot more than 10% difference -- in fact, it's actually about a 15.3% "width advantage" for the rears! Again, this is not a photo editing trick: those of us who ordered new sets of these tires from Tire Rack can remember that they really did look like that when stacked side by side.
But that's just the beginning; there are two other *big* differences.
First, notice how rounded the edges of the front tires are, and how square the shoulders of the rear tire are. This means that the rear tire actually puts a bigger *percentage* of its section width on the ground than the front tire. So even if they were the same width, the rears would still effectively be "wider" just because of its shape! How much wider? This is harder to quantify, but let's conservatively call it a 5% "shoulder advantage".
Finally, notice how wide the tread *gaps* are on the front tire, and how narrow the gaps are on the rear tire. This means that a bigger percentage of the rear tire's contact "patch" is actually touching the ground. So even if the front tires were the same width *and* the same shape, the rears would STILL put more "rubber on the road". I actually tried to quantify this by processing the tread images so that the rubber was pure white and the gaps were pure black. Then I simply measured the percentage of each tread pattern that was pure white. Here's what I found:
In the left side of the image, we see that over 78% of the rear tire's contact patch is actually rubber; but for the front tire, the percentage is less than 72%! That's a "tread pattern advantage" of about 9% for the rear tire!
So let's put all this together: The total "grip advantage" of the S02 rear is the product of all of its advantages: grip advantage = raw width adv. * shoulder shape adv. * tread pattern adv ~= 1.15 * 1.05 * 1.09 ~= 1.32. So the rear S02 actually put down a little over 30 percent more rubber than the front!
So if the tire specs were made to reflect the actual difference in "rubber on the road", what would the AP1 stagger actually be? Well, as krazik points out in the link above, the rear tire would be rated as 245/45R16; therefore if the fronts are ~32% narrower, that's equivalent to a 185/60R16 front tire -- in other words, the tires actually have a whopping 60mm of "effective stagger"!
OK, fine, but the suspension was designed to accommodate the difference, so where's the danger? Well, there were plenty of owners who replaced those S02s with all-season tires, snow tires, or just a different brand of performance tire -- but of course they used Honda's specs, and bought "regular" 205 fronts and 225 rears. Suddenly the rear of the car had *far* less grip relative to the front -- with predictable results.
Finally, there's one more bit of danger inherent in the rear S02s: that narrow tread gap only got narrower as the tire wore down (and Honda advised owners it could wear in as little as 10K miles!). Here's a photo of a new one vs. a worn one:
That worn tire was fine in the dry, but it was a genuine handful in the wet. I vividly recall a white-knuckle highway drive on worn rear S02s in a rainstorm: I was hydroplaning at 45-50mph, while traffic around me passed serenely by at 70+.
The moral of this (too-long) story: if you still drive an AP1 on the OEM 16" rims, follow krazik's advice and at least get a 245 tire for the rear. You can also go narrower than 205 at the front (if you can find it), but the wider-than-spec rear tire is absolutely essential. But even if you're just interested in handling, it's good to know what F/R grip ratio the original suspension design was based on.
Stay safe out there!
Edit: P.S. I posted this here in the Suspension forum (rather than Wheels & Tires) for a couple reasons: this post is more about the effect of the tires on handling, rather than simple tire fitment (which the wheels forum is usually more concerned with); also the Wheels forum already has krazik's sticky post about getting 245 rears.
Edit 2: Lol as Doc Hudson said, I guess my mind's been changed for me!
Excellent work!
Do you happen to have the complete specs for the S02 OE tires? I am looking for diameter and rotation per mile data.
