Interesting and love that they used a CRX. Concerning the selected vehicles vs. rear drive Porsches:

I find myself at more and more autocross events every year. I've had a lot of instructor rides and my wife is a great driver... so I'm pretty sure my skills are improved. I'm now at a place where I usually finish in the top half of similar cars. Recently, my improvement has slowed (or my consistency is better), so now I think my base Boxster is ready for better tires. I drive the car to work about three days a week, so I'm not interested in modifying it into an autocross vehicle.

My current tires are low-end Bridgestones. Over the years, I have replaced the fronts once, and the rears twice, but I was never at a place where all four were sufficiently worn to replace the full set with a different brand. My friends tell me not to mix different tire brands on the car.

So, here's the question... my local Costco has Michelin Pilot Sport Cup tires that fit my rears. I can spring for these, plus some new Michelin Pilot Sport PS2s for the front at the same time. Will this make me a happier autocrosser? and what will happen when I street drive here in California with these tires?

I run Michelin Pilot Super Sports on the front and rear of my '01 Boxster. They are mounted on Porsche Sport Design 18" wheels. IMHO, they have plenty of grip on the Auto-X circuit and are great on the street. I think you would be pleased with the Super Sports.

I got my PSS's a couple of months ago from Tire Rack; they were available at my local Costco, but only by special order.

Bruce
2001 Boxster
1984 Carrera Targa
1977 911S (Euro)

That's what it reads like.

But let's back up. For showroom stock, PCA requires 140 treadwear. For street prepared, SCCA requries 200.

There are a set of tires that are designed to meet these specs, informally referred to as "cheater tires". For example, i run the Bridgestone RE-71R both street and AX, 200 treadwear, SCCA legal. Street name: Hoosierstones.

They are relatively poor in wet and awful in cold.

A step up on the reality meter would be the kinds of tires you refer to. Depending on your car and wheel size, SuperSports may nto be available ( I cant get them for my 986). The PS2s are quite good too. So are Bridgestone RE-11s, although they are heavy, noisy and rough riding.

You first need to think about what your priorities are.

Grant
(NNJR PCA AX chair)

Grant

gee-lenahan-at-gee-mail-dot-com

actually i like them a lot and enjoy them as everyday tires. But they are shaky in wet sand cold - need to be relaistic here.

Grant

gee-lenahan-at-gee-mail-dot-com

[grassrootsmotorsports.com]

As Grant said, RE-71 is the hot ticket de jur, but will be size dependent and I'm not sure how great they'd be on the street.
What sizes are you running.

I think I recall this correctly: Car and Driver and/or R&T would do tire tests or tech articles that mentioned slip angles and the effect on over- and understeer. Would it be somewhat problematic to select tires with slip angles that favor good handling with front-engine front-wheel-drive cars vs. rear/mid-engine rear-wheel-drive ones?

In fact, its not clear to me which car will run bigger slip angles. I think they will simply run them at opposite ends of the car.
Correct me if I'm wrong.

The big things to know are:

1. grip
2. behaviour at the limit / recovery
3. steering feel

Then, on track0-ish tires,

4. wet behviour
5. all that practical stuff (NVH, wear) whcih we know stink

Grant

gee-lenahan-at-gee-mail-dot-com

Quote
Spanky
I find myself at more and more autocross events every year. I've had a lot of instructor rides and my wife is a great driver... so I'm pretty sure my skills are improved. I'm now at a place where I usually finish in the top half of similar cars. Recently, my improvement has slowed (or my consistency is better), so now I think my base Boxster is ready for better tires. I drive the car to work about three days a week, so I'm not interested in modifying it into an autocross vehicle.

My current tires are low-end Bridgestones. Over the years, I have replaced the fronts once, and the rears twice, but I was never at a place where all four were sufficiently worn to replace the full set with a different brand. My friends tell me not to mix different tire brands on the car.

So, here's the question... my local Costco has Michelin Pilot Sport Cup tires that fit my rears. I can spring for these, plus some new Michelin Pilot Sport PS2s for the front at the same time. Will this make me a happier autocrosser? and what will happen when I street drive here in California with these tires?

You are on your own mixing tires on these cars. Some have reported no problems others have reported problems.

As an aside if you are not replacing the front tires every 2nd set of rear tires, you are -- this is my experience with my Boxster -- running the front tires too long. When the 2nd set of rear tires are worn and due to be replaced, this after around 20K miles, and the 1st set of rear tires likewise delivered around 20K miles of service, the front tires then have (obviously) around 40K miles on them. While in my experience the front tires have quite a bit of tread left the tires are hard and slick and noisy due the heat cycles.

One time I left the front tires on and just put on a 3rd set of rear tires. I drove the car but the car's road feeling deteriorated as I drove. The car felt bad enough on the street, but I can only imagine how bad it would have felt/been if I auto-crossed the car.

I can't recall now how many more miles I drove on the fronts but I finally replaced the front tires and the car was transformed and for the better. I recognized that while when I was replacing the fronts after around 40K miles and with the tires looking like I was throwing money away based on the amount of tread left, in fact the front tires were very near the end of their life, their service life.

Have to point out the best tires for the street will almost certainly not be the best for auto-crossing. But it is important to note on the street the tires have to endure whatever potholes, rocks, glass, debris, gets thrown at them. They have to offer safe levels of grip under all conditions: cold, hot, dry, or wet. They have to or should deliver reasonable service life and ideally not cost an arm and a leg when it comes time to replace them.

On the auto-cross track/course the tires have in some ways an easier time of it.

My recommedation would be to buy a good set of street tires, something N-rated of course, and probably Michelin, and use these. You get good/excellent street driving service from them and on the track they'll be good enough.

If you need better tires on the track some Boxster owners haul a small trailer behind the Boxster with a set of tires/wheels on it for the auto-cross track. Or you could arrange to have the wife or another family member or a friend drive with you to the track/course in another vehicle that can haul or carry a set of track tires/wheels.

Have to mention if you get too sticky of tires then you really need to consider some modications to the engine to help it withstand the high g-forces and the compromise to oiling that can arise from the higher g-forces.

IOWs,if you feel the street tires breaking loose on the auto-cross track/course, while you can fret about the effect this has on your time, be consoled that in breaking loose the tires are as a side effect keeping the g-forces down and this could be saving your engine.

That unlike a major race track with sustained high-speed and G sweepers (WGI's outer loop, Lightning's lightbulb, thunderbolt's octopus, LRP's Big Bend), an AX track typically changes direction so often that the oil does not get pulled to on wall or the other - its constantly sloshing back and forth.

Agree with all else for the most part.

I would never mix front to rear.

I do however drive my RE71-Rs as my regular, day-to-day tire. As long as its not too wet or cold, they are great on the road. If its wet, slow down!

G

Grant

gee-lenahan-at-gee-mail-dot-com

Quote
grant
I do however drive my RE71-Rs as my regular, day-to-day tire. As long as its not too wet or cold, they are great on the road. If its wet, slow down!

G

Grant
How is the wear on them?

In 19" sizes they are not terribly expensive but the reports of quick wear is disconcerting.

On the track, they dont appear to handle heat and scrub well and the wear is quick, maybe 50%-100% faster than 888s, for example. I will say they are very predictable at the limit, but the sidewalls are soft.

AX, at least with a light car like mine, yields modest wear. Yes, they scrub - very fast compared to actual street tires, but OK.

On the street i dont notice horrid wear.

I've now had them on the base 2004 (Burgundy) car for about 10 months, maybe 3,000 miles including ~7 AXes - most of those long, fast AXes at the Meadowlands which are relatively hard on tires. Street driving is often spirited - since i no longer commute,its either put-put to the supermarket, or "let's make this errand fun". So i would say much harder than normal use. Wear is barely evident, as expected.

I would guess they wear on the street 2X as fast as actual street tires, and on the track 1.5-2X faster than the best street/track tires (cups, 888s, ...).

For my use with street and AX they will cycle and time out sooner than they will wear out I suspect. They may in fact be transferred to the track car after 3 years tp die and exciting death.

I really like them as my only tires (aside from 16" snows) on my street car / AX (SS1, C-street) car. PS2s would be far inferior on grip; 888s illegal, CUPs not available, PSS not available. The only really alternative is another very good choice, the Yokohama AD-08R.

A terrific, cheap, "everything" tire (bit not competitive in AX at hgih levels even for street) is the BFG g-force sport comp-2. They are 85-90% of a PS2, wear better, cost much less, snowflake rated.

G

Grant

gee-lenahan-at-gee-mail-dot-com

Sounded like an interesting substitute for R comps for track days but the wear kills it.
I think when these NT01s are done I'll got with RE-11s; longer wearing, not bad in wet so if you drive them to the track you'll get home in one piece and with enough traction to have some fun.

less grip than NT-01s ( which everyone says are pretty terrific)
very noisy
very heavy
very long wearing, for a track tire

Grant

gee-lenahan-at-gee-mail-dot-com

They are likely the best bang for the buck.

I plan to try BFG R-1Ss someday

Grant

gee-lenahan-at-gee-mail-dot-com

The guys I know that use them thought they wore faster than the NT01s and marginally stickier, while being more expensive.

Sounds like the R-1 is considered the hot tire today with R-comps.

First, 888 and NT01 are made by the same company to ( and one one can prove this one way or the other) the same compound spec.

The NT01 has a thinner tread. It is lighter, and has a fairly solid outer shoulder. Most prefer it from a pure performance perspective.

But he 888 is pretty armor-plated - LARGE volume of HEAVY rubber all around (which is why it wears well and handles heat I'll wager).

So I'd reverse the wear order of those two. Both are very good and good value. Both I think stick better and have better steering response than the Re-71R, but then, neither meet either PCA or SCCA stock-class specs.

Yes, i hear nothing bad about the BFG R1 except that its, well, a slick and therefore useless in the rain or cold - which i seem to get lots of!

Grant

gee-lenahan-at-gee-mail-dot-com