M030 springs/shocks and GT3 anti sway bars

[bjarne996]

I have a 1998 996 C2 with standard european suspension and 265/35-18 rear tires.

In order to improve grip and handling I am considering changing to:

-285/30 rear tires

-Euro M030 springs/shocks

-GT3 adjustable anti sway bars

I am thinking about the GT3 swaybars since I want to use the wider rear tires, but do not want any more understeer!

Has anybody got any experience with this combination?

[c70Pete]

I have a 1998 996 C2 with standard european suspension and 265/35-18 rear tires.

In order to improve grip and handling I am considering changing to:

-285/30 rear tires

-Euro M030 springs/shocks

-GT3 adjustable anti sway bars

I am thinking about the GT3 swaybars since I want to use the wider rear tires, but do not want any more understeer!

Has anybody got any experience with this combination?

going wider in the rear will give you more understeer... stay with 265 in the rear

EURO M030 and GT3 sway bars are an excellent combination.... but stay away from the 285 in the rear... it will make your car slower as those tires weigh more *and* create more friction.... Michelin PS2 is a nice 18" tire that is lightweight for 265 size...

[bjarne996]

going wider in the rear will give you more understeer... stay with 265 in the rear

EURO M030 and GT3 sway bars are an excellent combination.... but stay away from the 285 in the rear... it will make your car slower as those tires weigh more *and* create more friction.... Michelin PS2 is a nice 18" tire that is lightweight for 265 size...

Yes, the wider rears will give more understeer, that what I wanted to counter-act with the adjustable sways.

The wider tires will provide more lateral grip, and thereby allow slightly higher corner exit speeds.

I do not think the weight difference will play make any measurable difference in how fast the car is or feels. If anything the slightly smaller tire circumference of the 285/30 compared to the 265/35 will make the car accellerate better!

Anyway, have you got the M030 / GT3 Sways combo on your car?

[c70Pete]

going wider in the rear will give you more understeer... stay with 265 in the rear

EURO M030 and GT3 sway bars are an excellent combination.... but stay away from the 285 in the rear... it will make your car slower as those tires weigh more *and* create more friction.... Michelin PS2 is a nice 18" tire that is lightweight for 265 size...

Yes, the wider rears will give more understeer, that what I wanted to counter-act with the adjustable sways.

The wider tires will provide more lateral grip, and thereby allow slightly higher corner exit speeds.

I do not think the weight difference will play make any measurable difference in how fast the car is or feels. If anything the slightly smaller tire circumference of the 285/30 compared to the 265/35 will make the car accellerate better!

Anyway, have you got the M030 / GT3 Sways combo on your car?

Hi,

interesting theory....

I have the ROW M030 with 17" 225/45/17 and 255/40/17.... when my rears wear I will get 265/40/17 - the ROW 030 kit dials out some of the nasty understeer found on the 911 ... but going 285 is pretty wide... you think the car will be faster with 285 in acceleration.... what percentage difference in diameter exists between 285 and 265?

[bjarne996]

Hi,

interesting theory....

I have the ROW M030 with 17" 225/45/17 and 255/40/17.... when my rears wear I will get 265/40/17 - the ROW 030 kit dials out some of the nasty understeer found on the 911 ... but going 285 is pretty wide... you think the car will be faster with 285 in acceleration.... what percentage difference in diameter exists between 285 and 265?

I have 265/35- 18, for which 285/30-18 is a Porsche approved alternative.

Tire height is a percentage of its width, hence two "tire heights" in addition to the rim size will give total wheel/tire diameter.

The circumference is PI (~3,14) times the diameter.

The circumference of the 265/35 should be:

PI * (2 * 26,5 cm * 35% + 18" * 2,54 cm) = 201,91 cm

The circumference of the 285/30 should be:

PI * (2* 28,5 cm * 30% + 18" * 2,54 cm) = 197,35 cm

Hence replacing the 265/35-18 with 285/30-18 will reduce rolling distance by approx 2,3%.

Edited January 25, 2009 by bjarne996

[c70Pete]

Hi,

interesting theory....

I have the ROW M030 with 17" 225/45/17 and 255/40/17.... when my rears wear I will get 265/40/17 - the ROW 030 kit dials out some of the nasty understeer found on the 911 ... but going 285 is pretty wide... you think the car will be faster with 285 in acceleration.... what percentage difference in diameter exists between 285 and 265?

I have 265/35- 18, for which 285/30-18 is a Porsche approved alternative.

Tire height is a percentage of its width, hence two "tire heights" in addition to the rim size will give total wheel/tire diameter.

The circumference is PI (~3,14) times the diameter.

The circumference of the 265/35 should be:

PI * (2 * 26,5 cm * 35% + 18" * 2,54 cm) = 201,91 cm

The circumference of the 285/30 should be:

PI * (2* 28,5 cm * 35% + 18" * 2,54 cm) = 197,35 cm

Hence replacing the 265/35-18 with 285/30-18 will reduce rolling distance by approx 2,3%.

2.3% is ok... its when you get beyond 4% its start to play havoc with the ABS system.

what model of tire are you running for 265/35/18 ? what model of tire are you gong to run for 285/30/18... ?