Dr. Car

I've got a set of CCW C14 rims in sizes 18x9 and 18x12 on order. I had other tire plans, but when I saw the prices on Kumho Ecsta V700's, I had to consider this tire (I would shave it 4/32"). It comes in 245/35/18 and 305/30/18 which obviously would be a perfectly good fit and diameter front and rear for my 997S. However, the V700 also is available in a 265/35 and a 335/30 - which would be awesome although I would fear for rubbing.

Does anybody have feedback on the Kumho Ecsta V700 or have information about somebody attempting to run 265s front or 335s rear? For purposes of this exercise let's assume the wheels have an offset similar to OEM, and other than being wider won't be a source of clearance issues.

I am aware, from my searches on this forum, that a 245/305 front to rear split is great and that 315s can fit too. I saw rumor of 265 fitting the front and a 325 fitting the rear, but it seemed to be second hand information.

RonCT

When I was shopping for wheels and R-comps, I was told many things about my 997S... 245 front was about the limit without rubbing, so 235 or 245 would be it. For the rear, 305 was the comfortable limit, so 295 or 305 would be fine. That pointed to 235/295 PSC or 245/305 RA1.

For both, the optimal wheel widths were 8.5" front and 11" rear (see tire specifications). There's been some debate here as to why all wheel makers (Fikse, Forgeline, BBS, etc.) suggest 8.5 and 11", why CCW used to suggest those sizes, and now recently CCW is saying 9 and 12".

I found that 18x8.5 and 18x11 is a perfect fit for the 245/305 RA1s I'm running. They are exactly "optimal" widths for the tires per the maker. Wider and I'd have more metal spinning around -- heavier and unsprung to boot. If there were some evidence that 265/325-345 would fit and run well, I might consider wider wheels. But at those widths I've been told by wheel people and race preparers that with a street car that can be just too much rubber.

I'm also sensitive to the computer issues with the 997 product. We have ABS, PSM, and the speedo / odo to consider. Porsche changed the rear wheel diameter on this platform from about 25.5 to 26.5". There's some wiggle room, but I wanted an R-comp that matched as close as possible -- and I believe the RA1 and Hoosier in 18" do. PSC (and probably others) are about 25.5 front and rear -- I didn't want the chance issues. One Porsche 997 race car preparer said that if you go too wide, you'll probably end up with ABS / PSM issues -- so 245/305 is just fine.

mdrums

you want 245/40/10 front and 305/35/18 rear. I am using the same sized wheels you have with these tire sizes and they work perfectly. That keeps the diameter the same. You can get away with 305/30/18 rears from what I hear but the rear tire diameter is much less.

nkhalidi

whaaaa? What is this "too much rubber" you write of? I say stuff as much under the car as possible, while keeping a reasonable stagger (if necessary/applicable).



[I am only half-kidding. My street M3 has 275s all round.]

Carrera 69

I have 9x18 and 12x18 Forgelines with 245/305 RA1's. I find they are a perfect set up. The RA1 is a very foregiving tire, they last long(Wear/heat cycling) and they get sticky quickly even if the air temp. is a bit cold. Unlike the MPSC's wihich don't like cold air and along with the Hoosiers they heat cycle out very quickly. Full tread, they RA1's are a bit squirmy but they sill hang on, if you shave them they are great.

RonCT

I wanted BIG rubber up front and at the rear and was talked out of it for a couple reasons... So, I'll make due with 245/305 on 8.5/11" wheels

Dr. Car

Right, but a 305/30 paired with a 245/35 has the correct stagger and shortens the gearing and ride height as well, both of which sound like good things. A 265/35 and a 335/30 would also have the correct stagger.

So, if I run the 265 and 335 successfully I will revolutionize 997 track tire fitments?

mdrums

If you could get those to fit with out rubbing they should really help on turn in! Yes I liked liked shorter gearing the 35/30 profile would give and could use it with the taller gears in the tiptronic too. From what I've heard and read as long as you stay within 2-4% difference between front and back diameter you will not scre up PSM and ABS.

IF the 265/335 fit let us know I do not think they will.

Dr. Car

I got some more information today from someone who's experimented with wheel offsets and different tire sizes. With the right spacing, a 335 will fit in the back, but a 265 will not fit on the front. Putting a 335 on the back without a commensurately larger front tire would probably just create some bad understeer. Thus, I decided to go with the 245/305 setup. I'll report on my results after my track days and autocross.

RonCT

That's what the experts told me as well back when I was shopping and so 245/305 pointed to 18x8.5 and 18x11" as optimal wheel sizes.

mdrums

Dr. Car I have the same size CCW wheels you are getting and the same tires and sizes RonCt has. They work great for DE and driving to and from the track.

Enjoy!

Dr. Car

245/305 Kumho Ecsta V700s on the 18" CCWs were great. Considering the low price, I highly recommend them. I'm always hard on tires, but it appears that the V700s wear faster than RA-1s, as I'd heard prior to my purchase. Whether they are stickier as well, I have no basis for comparison.

So, if you want to run 18's for the track, here's more encouragement. If you want to get big 18x9, 18x12 forged aluminum CCW C14 wheels, another big plus... they look great and are light. 22# front, 23# rear by my measure. And if you want to get inexpensive R-tires on your track car, by all means try to Kumho Ecsta V700s or the Victoracers (I've used and enjoyed those before).

mdrums

Dr.Car what were the prices on your tires?
thanks! Mike

Dr. Car

$210 for rear 305/30
$178 for front 245/35
$120 for shaving, heat cycling all four tires. I had them shaved to 4/32; TireRack info says these tires need to be shaved for dry track use.
$80 shipping to California.
All told just under $1000.