Anyone have experience with 245/35/19 fronts instead of the stock 235/35/19? If yes, what did you think of them and what brand were they? Did they rub at all?

I'm thinking of going with that size on the front to help reduce understeer. Any thoughts? I have the stock 5mm spacers front and rear on my 2007 C2S.

I'm also considering upsizing the rears to 305/30/19, same as C4S, instead of the stock 295/30/19. Any thoughts on that? Same reason as above - hoping for more grip, but front is more important than rear to me - I hate understeer.

Thanks in advance for your help.

 

Ok, you do not need this size tire to control understeer.

Also you will be increasing the tire diameter by .3" thus making the front end higher off the ground. Also by goin gwith 305's in the rear you will be increasing oversteer too.

1st get a good alignment and max out the front Camber and set the toe to zero. If you have stock PASM this will be right around -1.03. Make sure the rear camber is no more than -1.5. More rear camber will cause more understeer.

I track my car a lot and for the street I never experiance bad understeer. I use the throttle to control this as well.

To really help have some GT3 lower control arms installed and align to -2 camber front and -1.8or9 rear. This with proper tire pressure and driving skills will solve understeer.

 

I have gone with the 305/30/19 rears and it looks a lot better, ride seems the same, grip is slightly better. I have actually gone to 20" wheels now and find the 255/30/20 fronts grip well but rub slightly on full lock turns. I don't have any experience with the 245/35/19's personally but I know a few track guys that prefer that setup up front. Ultimately, only suspension 'tweaks' will help with the understeer issue. Mdrums knows what he's sayin'.

 

I have 245/35-19 front, 305/30-19 back. Looks GOOD! I agree 245 in front is not needed, but I like that little extra width. Pics:



Yes, it raises front of car...By 1/7 inch! Big deal. Yes, it means your Speedo will read slow... By 1.1% (.7 mph @ 60). Big deal.

So, if you like idea, go for it!

 

Speedo will be based on the rear tires not the front I believe. Love the look of your car...I to am considering the 245/305 setup as it will balance out the car. I figure if you are increasing the rear by 10mm, you should do the same for the front to keep it balanced.


Dave

 

I think you mean it will increase understeer, the 305's should reduce oversteer.

Dave

 

I dont see how 20s are going to help anything. When we were all involved in GT3s we were going from 19s to 18s to improve handling on the track. 20s are going to upset the handling of a C2S. There in an article in Excellence about how to NOT go to 19s on the C2, it will ruin the handling. So will 20s on the C2s

 

Absolutely! 18" for track, 19" for street. The lower sidewall actually ads up DECREASING contact patch in cornering for a like tread width. Thy also absorb less surface irregularities and end up bopping around a bit more.

 

Porsche also said that the PASM on the S was engineered for the 19's. Not to mention that tire selection has gotten better the last few years to have some good choices for R compound tires for the 19".

Dave

 

Would it be possible to go 315 on rears on a 997S on standard 19 inch wheels, without touching the fronts? Would this be messing with the understeer or oversteer?

 

Dave07997s, is it just me, or do the sidewalls of the rear tires make the tire look like it's streched over the rim....as if the rear tires should be wider? Shouldn't the sidewalls be straight up/down...no angle as is shown by the front?

J

 

If you are referring to the 295's on an 11" wide wheel then it is stretched to the limit. Porsche did this to give the sidewall the maximum support and to give the tire a maximum footprint. If you notice most manafacturers who produce a 295 tire recommend a 11" wheel as the max in width for these tires. The 305's look perfect...I put 305's on my 997S and although it doesn't look really that much wider it does seem to fit the rim a little better. Now you move to a 12" wide rim and the 305's will be stretched even more than the 295's were with an 11" wide rim.

Dave

 

Yes, thanks for the correction...try to type while the wifey was calling for me.

 

Interesting point that due to the width of the fronts, the 10mm increase will be a larger proportional increase than a 10 mm increase to the rears. Going to a 245/305 setup should still decrease understeer. I find these cars really understeer when going into corners hard. I guess that was the way to prevent drivers from diving in hard and finding themselves in a major oversteer situation. If you know how to drive, it is just kinda wierd since you need to deal with the understeer first and then power on to balance the car and get the tail to come around.

On BMW's I found that messing with the tire size and height had some effect on the ABS - it came on sooner as a result of the computer confusion. Anybody experience that here?

 

Ding, Ding, Ding, Ding...We have a winner!

Mike, I did my 21st track day in this car, and I learned a whole bunch of new things. These cars are a lot harder to learn how to drive properly, but the journey is a lot of fun.