M5 with 305 square 200tw setup on track: Waterford and Grattan

[vafan13]

I took my M5 to Grattan for the second time over memorial weekend, and while I had a great time, it just had too much understeer compared to my 900lbs lighter 01 Cobra runjing 275 square 200tw tires. So, I decided if I was going to keep tracking it, I'd have to follow spiff into madness and run a 305 square setup on 19x10.5s. However, I went a step further and instead of PS4S I chose Kumho V730s, a 200tw tire. I chose the V730 for a number of reasons:

1. They run narrow. I wanted this as 305 is at the limit for a 10.5.
2. The outer tread block works well with camber limited cars. This is a big pig and I'm not planning to do the extra-camber UCAs.
3. It's asymmetric and thus has a minimal rim protector lip on the inside. This is important, as due to the front knuckle shape, the first place to rub will be right where the tire mounts to the rim.
4. They wear slowly
5. They're relatively cheap, at $140/set less than RT660s, another popular 200tw.

With the ET45 wheels I'm running 17.5mm spacers front, 12.5mm back. Could run a bit larger back but already had 12.5s. Anyways, moving on!

Waterford Hills:
https://youtu.be/c1g1rLrLUUs

I never intended to take the M5 here, as it's tight and very narrow, with small straights. Not great for a nearly 4400lbs, 500+ whp car. However, my Cobra had issues so last minute prepped the M5 for its first time out on the new shoes. End result? Despite 4hrs of sleep and leaving a lot of time on the table, I managed to beat my previous PR with the Cobra. I was extremely impressed with how well it did on this track, given its size.

Gingerman:
https://youtu.be/iPJhgrVOzQk

Much better track for our cars with a number of straights to utilize the horsepower. First day wasn't great due to a combination of poor weather the 1st half (wow these tires hate rain) and a slow overcrowded run group, but day 2 was great. This was a new track to me so was both getting used to the wheel/tire combo more plus a new track. While I know there's a lot more time I could shave off with further experience there, I was still quite happy with the end result. I will say, though, that doing a track event with the Chicago Porsche club made me feel poor! �� In addition to a lot of fantastic Porches, there was a guy absolutely tearing it up in 296 GTB. Really impressive, and mad props to the owner for not only taking it on track, but running it hard. Off the track highlight for me was definitely having the owner of a beautiful C8 come over and take a picture of my car because he liked the color so much. (Sakhir Orange ftw!)

My plan is to next get back to Grattan mid-September with the BMW CCA and see how much faster I can go with the new tire setup. Hoping for 1:30s, if not 1:29s!

[spiff]

Dude this is awesome !!

Those tires look MEATY!!!!!

Stoked that the setup worked for you and you enjoyed the car this way.

Keep the posts coming !

[M5_Raz]

Looks and sounds really happy on the track! Do you change the oil after a track day?

[vafan13]

Originally Posted by spiff

Dude this is awesome !!

Those tires look MEATY!!!!!

Stoked that the setup worked for you and you enjoyed the car this way.

Keep the posts coming !

It's a huge difference compared to running stock wheels with PS4S. better steering response, much better turn-in and, of course, much better maximum grip. I'll be sure to post again after I go to Grattan in a few weeks. Excited to see how much time I can shave off compared to when I was there in the spring with the stock setup.

Originally Posted by M5_Raz

Looks and sounds really happy on the track! Do you change the oil after a track day?

If the oil had low-ish miles overall and only 1-2 track days on it, no. I haven't seem oil temps above 235-240 (hard to tell) on track and the last oil I sent to blackstone (w/TBN test) after a 2-day track event and 5500 miles still looked great. I did change it between the two above events, as that oil had ~3500 total miles and 3 track days on it at that point. Not sure if I'll change it again before 2-day Grattan event mid-September. Waiting to get the blackstone back from the last change.

[etnsandman]

This is pretty awesome. I've thought about a square 295 setup myself. Extended tire life warranty with 4 wheel rotations would be appealing.

[vafan13]

Originally Posted by etnsandman

This is pretty awesome. I've thought about a square 295 setup myself. Extended tire life warranty with 4 wheel rotations would be appealing.

If you stick with 20s, 295/30 is the way to go. I was hesitant to do 295s on 19s, as 295/30r19 is 1.3" smaller diameter, which seemed like too much. One could try 295/35r19, but that's a rarer size, so it's either RT660 or A052.