moving to trcak tires (r888's) ,any opinions on 295's vs 305's for rears, aside for the cost factor

 

Both sizes will be fine. I say go with the 305.

 

I am looking to do a PE track day(s) for the first time ever this year and I am considering mounting track tires on my snow wheels (Carrera III 18 inch).

Other things being equal, doesn't a wider rear tire promote understeer (maybe not a bad thing for a less-than-expert 911 pilot)?

On the subject of tracking our cars, is there a consensus on whether it pays to swap out the brake pads for the day? Aside from the performance benefit, I'm more concerned with preserving the rotors and not burning through OEM pads. I would guess as a novice the stock set up is fine for a DE day, but at some point does it pay to swap the pads?

David

 

For a novice driver, leave your car stock. Your rotors and OEM pads will wear out with use, it is a fact of using them.

As for larger tires, I don't think that they are really going to make a difference between a 295 and 305's. I run 315/30/18's and can get the back end to slide out by just touching the gas.

Your 18" snow wheels might be too narrow, I think that they are only 10" wide, I suggest that you stay with a wider wheel to allow wider tires, do enough DE's and you will want as wide a tire as you can fit.

 

stock 18" wheels are 8" front and 10" rear and take 235mm front 265mm rear.

mounting wider tires not going to do anything good as active contact patch will be determined by rim width. so there is no workaround here but having different
set of rims with 9"&12" or 8.5"&11" widths. First set will let you use 245mm/315mm tires - second is 235mm/295mm, some people mount 245mm/305mm on those rims but again I was told it will be waste on money as it will not really work properly.

What I am not sure is how exactly 9" and 12" rims fit into narrow body car, but apparently plenty of people use such wheels, so it should be fine. Problem with that is that I do not think any cheaper 18" rims like allegeritas exist in 9" and 12" with narrow body 997 offsets.

 

If you have dedicated track tires, why not go with slicks? Unless, of course, you have to drive to the track on the tires. But even then, I suggest getting a trailer to tow with your car, then you can bring more tools, too.

 

I have a 997 S and was thinking about getting some slicks but a PCA racer told me that they were not a good idea with a stock suspension. too much grip would be too hard on a stock set up. he said to get an aftermarket suspension before going to slicks. anybody agree with that?

 

Let's keep this in perspective, the OP is talking about a 1st set of track tires, so slicks should be off the table. A couple of added notes. You want to try to keep the tire diameters similar to OEM, which means about 25.5" front and 26.3" rear. Some track tires are designed to 25.5 / 25.5, so I wouldn't put a "too small" diameter on the back of my car.

For 19s, I found the R888 in 245/305 perfect on 8.5 / 11" rims. I don't know who would say 305s won't work on 11" rims when Toyo itself suggests 11" as the optimal rim width for the 305. For 18s I love the RA1 in 245/305 - just a great all around tire for cold, wet, dry, hot, whatever. It's DOT street legal so fantastic for driving to and from the track.

With brake pads if you aren't in one of the advanced run groups, stock is probably fine for now. You'll know when it's time to change when your rotors get all gummed up with pad material transfer. It's not just a balancing act of wear on rotor vs. pad. I've tried for many years to find the "compromise" pad that does it all. OK on the street, and up to hard track use. It doesn't exist. The Porsche Sport Pad (basically a Pagid 4-2-1) is a reasonable hybrid, but it still squeals on the street and at advanced level track driving it's not enough pad. So, consider sticking with stock until you need to change, and then try the Pagid Sport (blue 4-2-1) pad as the next level.

 

305's

 

I will just add that changing pads is soooo very easy on the Porsche that I do it at the track unless it is raining (in which case I wait until I'm back in a garage).

 

Keep in mind that when you go to R-Comp tires you really should be useing a race pad.

Since you are starting out with DE's and you do not want to wear out your stock tires I suggest you get some street tires for your snow wheels.