Toyo R888 225/45-13 Tires On EF Civic
My Civic has a 4 speed transmission. While 3rd and 4th gears are quite reasonable, there is a big gap between 2nd and 3rd. Seeking to reduce this gap and improve overall performance of the car I looked for tires with a smaller overall diameter.
The "standard" size for the car is 205/60-13 or 205/50-15 with about 23" overall diameter. Turns out there are some tires made in 225/45-13 size with a 20.8" overall diameter - a full 2" less. This is nearly a 10% reduction; a similar effect would be achieved by going from a 3.888 to 4.250 final drive ratio.
To experiment I ordered a pair of Toyo R888 tires in 225/45-13 size and ran them at Watkins Glen.
I used 13x6 wheels that came with the car. These are narrower than recommended wheel width range for the tires, but the tire shop installing the tires experienced only mild inconvenience while installing the tires.
Fitment On Car
The tires fit in the front and rear without issues. I already have rolled and pulled fenders, thus I cannot speak to how well the tires will clear stock bodywork.
Here are some photos of the tires on the car:
With a 7200 rpm recommended redline for the ZC engine, the top speed I achieved on these tires was 111 mph.
At Watkins Glen I got to the top speed by 1/3 of the back straight, and had to lift to stop the car going beyond the redline. Here is a speed graph from my 2:20.70 lap showing how much time the car spends stuck at its top speed:
I started the tires at 49 psi hot and eventually bled them down to 41 psi hot based on tire pyrometer data. At 41 psi I had even tread temperatures on both front tires.
Despite even tread temperatures, inside half of both tires wore out way before the outside half did. What is interesting is that the tires - on both sides - were contacting track surface through the entire width of the tire. In particular, the outside edge was visibly used (although not worn much) right up until the effective shoulder.
I dropped 4 psi to 37 psi hot for the second half of Sunday and I felt that this did not produce an increase in grip at all.
Once I settled hot pressures at 41 psi the tires felt great. However, the grip level steadily decreased throughout the weekend, and even by the end of Friday I felt that the tires were performing worse than in the morning.
On Saturday I was driving much better and really started to feel the lack of grip compared to Friday.
The tires were completely worn out by the end of the 3-day weekend, which was the first time I managed such a feat, and this was with me not running some of the sessions as I had to change a brake rotor and then brake pads twice.
The tires are actually showing cords on the inside half. There is no tread remaining there at all.
Dropping pressures did not produce an increase in perceptible grip at all.
Grip fall-off was gradual throughout the weekend.
I read on a forum that someone was getting 15 heat cycles out of R888, and I estimated that I achieved that count between morning and lunch on Sunday.
I had the tires heat cycled by Tire Rack and their grip was most certainly not holding at a constant level throughout their life. I don't know if the grip would have fallen off quicker without heat cycling.
I ended up running a 2:20.70 early Sunday morning. By then the tires were way off their peak performance and I was also running on Wearever brake pads which somewhat compromised my braking distances.
I never experienced oversteer with front R888 and rear Toyo RR tires. The car was either balanced or understeering the entire time. Suspecting that RR were much grippier than R888 I moved front and rear tires around which created a really strange configuration.
Small Tires In Rear
To test the theory that RR were much grippier than R888, I ran 205/50-15 RR in the front and 225/45-13 R888 in the rear.
In this configuration the car had significant "reverse rake" - the rear was a lot lower than the front. The result was a severely weird handling car. It felt a lot like a boat or a car on very soft stock suspension - the rear was swinging like a pendulum and wanted to spontaneously go around the front. This was unnerving and I parked the car after a lap of this silliness.
Watkins Glen, Summit Point Main and Pocono Long/Double Infield courses are the ones where I hit ~110 mph anyway and these tires would take the car to its top speed in the middle of the longer straight.
Summit Point Shenandoah, Pocono North and Thompson Speedway would be tracks where the car should not hit its top speed with these tires.
Curiously I seem to achieve a higher top speed at Lime Rock than at Watkins Glen, despite Lime Rock being a pretty short track.
More testing needs to be done to determine if holding the car at its top speed is actually advantageous as the car accelerates harder everywhere else on the track.
I was most shocked by the rapid wear of R888 - this is the first time that I completely wore out tires in a single weekend. R888, based on this experience, is most certainly not my idea of a long wearing tire. I will not be buying any more R888 for DE purposes.
For racing, the concept of a 20.8" OD tire is still interesting. But I will try the other tires in this size - Hankook Z214 to start, which happens to be cheaper than the R888. Hoosier also makes A6 and R6 in this size.
225/45-13 tires cannot be moved to the rear axle without having the same size tires in the front, or the car's handling becomes completely insane. This effectively mandates running a square 225 setup to even out tire wear, or accepting more rapid wear of 225 fronts while running narrower and taller 205 rears.