Sportscar Mag Wheel and tire comparison test

[MINI-Fit]

A good article. April 08 Vol 66 No.4
SportsCar Magazine - sportscar racing

What did they test and find?

1. Plus size tires-
Keeping stock diameter similar they compared Hankook Rs2 in
205/50-15 vs 205/45-16 both on Motegi Traklite 1.0 rims on a Miata.

15"
Quicker launch
Easier to handle
More consistent run times
Corner Exit and braking distance better

16"
More wheelspin
Stiffer sidewall- easier to lock up brakes, more crisp initial turn in, transitional speed better
More difficult to drive at the performance edge
2 mph faster slalom speed

Lateral g-Force was same for both 1.01G
Overall lap times were very close (116.9 dirty vs 117.1 clean for the 15)
Overall 205/45-16 more difficult to control at the limit, more suited to experienced drivers.

2. Street tire vs R compound
Rota P45f 18x8 wheels on a B-stock RX8
Bridgestone Potenza RE-01R 245/40-18 full and 4/32" treads
vs
Kumho V710 245/35-18

V710
Better forward bite
Better corner exit
2 seconds better on a 40 second course
Addition of 24% stiffer front anti-roll bar reduced corner exit oversteer and reduced time gap to 1.7 seconds

3. Full tread or shaved Street tires

Full tread
Squealed much more
0.2 seconds faster
More easily overheated- required more time to cool down between runs

Shaved tread
More quiet except at limit
Handled heat much better

4. Wheel weight
Rota P45f 18" wheels at 21 lbs vs SSR comp in same size at 16 lbs each.
Run on Bridgestone RE-01R and Kumho V710s.

Street tires-
Runs were about the same- no real difference on time
Street tire grip may be a more limiting factor than rim weight.

V710s-
More consistent times and 0.2 seconds faster

A note-
Naturally your actual car and class will make a difference as do the weather conditions, road surface, and time between runs.

Perhaps the biggest challenge is to match your level of driving skill to tires that offer enough performance advantage and still remain within budget.

A stock FIT with limited camber and power may not be able to fully exploit having V710s vs RE-01Rs. In that case the RE-01Rs would be a better bet, it will cost less, last longer, give adequate feedback to the driver and be usable to drive to events requiring no wheel change.

The automatic Fit might do well enough with the RE-01R or equivalent.
A manual Fit could use either tire depending on your budget- likely more risk of wheel spin (then maybe 205/50-15) in lower gears.

[HEMI-Fit]

Got mine the other day but haven't had time to read it yet... My reactions in a nutshell:

1. 15 vs 16 - 2mph slalom speed is big, but not as big the perks of the 15's.
2. Street tire vs R compound - V710's just plain ROCK. Once I can get MY times within a couple seconds of a good drive in my car, I'll start to save my pennies...
3. Full tread or shaved Street tires - interesting that the full-tread tires were faster overall. I wonder if that's due to the auditory feedback helping the driver?
4. Wheel weight - interesting observation on street tires & weight. Again good news for me and my lack of driving skillz - I can't buy my way out of them... Oh, and V710's just plain ROCK.

BTW, MINI-Fit, is the Bridgestone RE-01R worth looking at in a 195/50 versus another extreme summer tire in 205/50? At $106/ea they're +/- $20/ea more than the Kumho MX in a 205/50? Granted, the MX's are a few years old now.

Thanks for the great recap and solid tech every time!

HF

[MINI-Fit]

Originally Posted by HEMI-Fit

Got mine the other day but haven't had time to read it yet... My reactions in a nutshell:

1. 15 vs 16 - 2mph slalom speed is big, but not as big the perks of the 15's.
2. Street tire vs R compound - V710's just plain ROCK. Once I can get MY times within a couple seconds of a good drive in my car, I'll start to save my pennies...
3. Full tread or shaved Street tires - interesting that the full-tread tires were faster overall. I wonder if that's due to the auditory feedback helping the driver?
4. Wheel weight - interesting observation on street tires & weight. Again good news for me and my lack of driving skillz - I can't buy my way out of them... Oh, and V710's just plain ROCK.

BTW, MINI-Fit, is the Bridgestone RE-01R worth looking at in a 195/50 versus another extreme summer tire in 205/50? At $106/ea they're +/- $20/ea more than the Kumho MX in a 205/50? Granted, the MX's are a few years old now.

Thanks for the great recap and solid tech every time!

HF

Comments-
1. Everything is a tradeoff or compromise. Some events hardly have slaloms while others have plenty.
2. Street tires can be quite good but usually it will take an Extreme or Max Performance Summer tire to make the competition sweat. All R compound tires are not equal, some are better suited for track with higher temperatures (Toyo Ra1, BF Goodrich R1, Hoosier R6). Hankook Rs2 and Falken Rt-615 are quite good too and less expensive.
3. Full tread did well because it was a relatively short course and they allowed for cooling of the tires between runs. If one had a longer course with less competition and you had to run more often then the shaved tire would have done better. Water spray will help cool the tire between runs.
Full tread is great for water but you risk overheating the outer tread areas that can lead to chunking (loss of chunks of tire tread blocks usually from track use and new street tires).
4. Weights- surprising that it didn't really make as much difference but they had heavy 18" tires (27 lbs each) and about a 25% loss in rim weight.
So 27 + 21 vs 27+16 or 48 vs 43 a 10% in overall weight.

Compare that with a Fit stock wheel and tire of about 34.4 lbs vs
Kosei K1 TS in 15x7 at 12.6 lbs and Kumho V710s in 205/50-15 at 18 lbs = 30.6 lbs for 3.8 lbs less and 11% weight loss.

The V710s seem to make better use of the lighter rims, street tires not much so for street use, lighter rims may not be as critical as estimated.

For the RE-01R in 195/50-15, you get a slightly more narrow tire but you can maximize effect by using a wider rim either 15x7 or 15x7.5". I think the RE-01R is better than the Kumho MX or BF Goodrich TA KD. 195/50-15 is smaller than stock which helps for any tall gearing but if you have shorter low gears the 205/50-15 makes more sense. Both are pretty easy to drive compared to 45 series sidewall tires.

Another new tire to watch is the Dunlop Direzza Sport Z1 Star Spec
195/55-15 $90 each 19 lbs Extreme Performance Summer tire should be very good in Dry handling, pretty good in wet. 200 treadwear. Not quite as comfortable for daily street use as the RE-01R.

In 205/50-15 there are also the Hankook Rs2 ($81) and Falken Rt-615 ($73) which are more durable and better priced but I don't think they are as good as the RE-01R on dry or wet.

Another topic is when to change tires- R compound tires don't last but some drivers will use them for more than one season well past their prime. I have seen worn Kumho Victoracers on a well tuned BSP class car beat all the competition on new tires event after event when driving skill counted more than equiptment. I could never do that but it goes to show that driving skill is what we strive for.

[Darkstars]

One thing to keep in mind is the Fit lacks power. Lighter wheels aren't gonna do much for a car that that light up the tires at will, on a Fit your not braking traction unless your dumping the clutch from a standstill. I think you'd see a greater effect on a underpowered car like ours.

[MINI-Fit]

Originally Posted by Darkstars

One thing to keep in mind is the Fit lacks power. Lighter wheels aren't gonna do much for a car that that light up the tires at will, on a Fit your not braking traction unless your dumping the clutch from a standstill. I think you'd see a greater effect on a underpowered car like ours.

Depends on gearing and transmission as well as tire grip.

Even with Kumho V710s warmed up, manual transmission otherwise stock Fit drivers have reported ample tire spin during autocrossing in lower gears and certainly during launch.

Same setup with automatic during autocross, no tire spin but much slower times.

It would be interesting to check out various wheel tire combos during autocross and see if lighter really does much. I'd guess only a little difference. Seems like moderately light is good enough unless you run R compound tires. Most of the result is based on driver skill.

[Darkstars]

well one thing I can say is switch from stock sport rims to Heliums on stock tires made a noticeable difference in straight line acceleration, not thats its fast now but it doesn't feel pathetically underpowered anymore. It at least has some pep to it now (08 sport 5-speed with an intake and heliums)

[HEMI-Fit]

If only they came in 15x6.0 +49 or better...