Recommended track day tire size?
 

I'm looking for tires for my dedicated track day Boxster. They need to be street-legal. I'm using 17" boxster s rims and will go for 255 rears. What would you go for up front? 235? Will I be able to run 235 on a staggered set of boxster s rims?

I think the spec boxster guys run 235/40/17 up front on the stock 7x17 wheels, and 255/40/17 on the stock 8.5x17 wheels. I like to run 225/45/17 on the front OEM wheels and 255/40/17 on the stock back sizes.

For tires, I am like a broken record, I like the hankook R-S3, 200 TW tire, good on track and lasts a long time. I have a trailer and sometimes drive my street tires to/from the track but I have got lazy and now bring them as spares and leave them on the trailer and drive on the R-S3 all the time :)

If this is a dedicated track only Boxster, and is only driven to/from the track, there are lots of good 200 TW tires, Bridgestone RE-71R, BFGoodrich Rival-S, Advan, etc. Then there are some street legal 100TW tires like Toyo R888 and Nitto NT-01.

What all can you get in Norway?

I can get most makes if I order in advance, but since I'm hoping to get them by Saturday my options will be limited by what is in stock. I was thinking more in terms of 100TW tires, but this may be too much for the street? It rains a lot over here, and I need to cross mountains on the 8h drive to and from the track.

I'm running PSS9s with SPEC racing springs. I have -2.5 camber front and -2. rear.

I ran AD08Rs on the Clio RS and liked them. I have not tried anything more track focussed. My mates are running Federal 595RS-R but they complain about what wet grip. The AD08Rs are good on a wet road, but may be a little tame on track.

I need to be able to use the tires also on a wet track. Are the 100TW tires capable of building heat and sticking on a wet track?

I don't have experience on that, I am new to the 100TW tires. I have a set of Toyo R888 that came with my trailer but I have only run them in the dry, and they are pretty worn down anyway.

In my experience, I'd say that the Toyo RA-1 is probably the best all-around tire for both wet and dry track racing. This tire is good in the rain but will likely be a little slower in the dry than a Toyo R888 or NT-01.

That is valuable information. Thank you.

One more thing - be a little careful on a brand new set of RA-1's with full tread depth in the dry; they can feel loose until they scrub in and get some wear on them.

I ended up with a set of Federal 595rs-rr in 225 and 255. I'm hoping I've made a good choice, but I had to go with what was available and within my budget.

You also probably can not put 235 wide tires on a 7" wheel, you need at min 7.5". 225's fit a 7" fine
YMMV

Actually, the 235's will fit fine on the 7x17 wheel. That is what Boxster Spec runs for the fronts in the staggered setup.

This is good advice. I would add the RE-71r to your short list of street capable track tires. It is rated as 200 TW but grips like 100 TW. It is better in the rain than all other 100TW tires as well.

I wonder if that is true with RE-71's. In looking at the spec, the min for them in 235 is 7.5" and I just ordered new ones in 225 for my 17x7 wheels.

Could Tire Rack be wrong :confused:

It's a stretch Jay but they will fit. The result of running 235s is a little more contact patch and a little less sidewall control. I have run both and usually prefer a 225 on a 7" wheel.

YMMV

I wonder which would be better with my stock suspension

At the OP.....can out get Nankang NS2R in Norway. Readily available in Europe.
They do 180, 120 and 180tw. I have the 180 'street' compound and are fine on the road

My preference would be 225. I expect exaggerated rollover with limited camber.

All I know run a square setup of 8.5x17 all around with Toyo RR's. For the street and track I would go with full tread 255/40 Toyo RA-1's...

I ended up getting a set of Federal 595rs-rr. So far I'm pleasantly surprised, especially in the wet on the street. When new you can definitely lean on them as long as there is not too much standing water.

I would not put 235s on a 7J rim. The 225s I have now are already wide for the rim. I have a bit of experimenting to do With tyre pressures before I can say anything definitive about the grip though. After some initial trial and error I cut 2 Seconds off my previous best of 1.50. howevwe, I'm still not consistent enough to be able to tell what is Down to the tyres and what is me improving.

Yes, indeed, the Toyo specs for the RR 235/40ZR17 say a minimum of 8.0" wide and 8.5 preferred.

Nevertheless, this is the spec size for the 17x7 front rim in Spec Boxster, and it seemed to work fine. Toyo doesn't make a narrower tire for 17" rims.

Of course, now most people have moved to the square setup--255/40-17 on 17x8.5 all around, which does meet Toyo's requirements.

For Autocross, I'm debating 17" or 18" Rims with RE-71R (225/255 and 225 or 235/265) respectively. I've got rims for either.

Go with 17's. They are a bit less $$ than 18's and no difference in performance
additionally 17" wheels may weight a little less that the same in 18". Same with the tires

RE$-71's are the goto tire. Just don't expect a long life, especially with a stock suspension as they are severely camber challenged.
You will see lots of wear on the edges

RE71R - swap L/R for extended life?
 

Thanks - really helps. My suspension is stock. Maxing out negative camber, but something is wrong in the back - can't get full -1.5, more like -1. Car is for racing and is a little banged up. Has the sport suspension 030 option!

Looks like the RE-71R can be swapped left to right. should help.

Something must be wrong back there, as I am not sure I could get to "just" -1 with my stock suspension, I was able to get up to -1.9. That is a pretty big gap. Can you share a picture that shows your rear camber eccentric along with the rest of the suspension on one side? Maybe that might reveal something?

About the only way to get real camber is to go with GT3 control arms. They are $$$

A good lower cost solution is to get the ROW 030 springs and add camber plates for the front
I run that setup M030 ROW struts and springs and tarret camber plates on the front
I get front -2.2 and rear -2.5

It made a HUGE difference in the car.

With GT3 arms, you can get camber in the mid to high 3's

Not sure what group you're planning to AutoX with, but check the rules because camber plates with PCA puts your car in a class you won't be competitive in. GT3 LCA's are great, but not close to free.

For autox I would suggest 18" wheels so that you can get the widest rear tire possible without losing sidewall stiffness. And you won't need to change sway bars. The car will have understeer, but I find that more useable than losing the back end. A lot will depend on how you drive the car.

RE-71's are terrific. You can flip the tires on the rim once the outer shoulder wears. I got over 100 runs from the fronts (50 before flipping). Rear outer shoulder is now spent, but I can flip and have enough tread for another season. The car has mild camber with 2*F/2.2*R because it sees a lot of commuter time too.

I personally prefer oversteer to understeer. At least you can rotate the car. With a stock suspension, yea, the Boxster is a great handling car, but the difference is dramatic with mods and the right alignment. It goes from great to super-duper :)

Yea, you go from a stock class to a points based class. In theory you are classed with cars that have similar performance. At the end of the day, it all comes down to the driver.

Putting GT3 control arms would also put you into a point based class. Yes you do get a lot more camber. You really need to look at the entire suspension together as a system.

I humbly disagree that 18's are better for AX. I suppose the slightly shorter sidewall may make a slight difference, but you will be paying a lot more for tires. I would go with 17's and save the $$

It does depend a lot on your local ruleset but here in SoCal I preferred running 17s. I liked 255 square for tight AX and 225/255 for the track. I did run square for a while at the track, but the data was pretty clear and favored 225/255, especially at Fontana and Laguna Seca.