Experiences with 305/25/20 tires? - The Unofficial BMW M5 Messageboard (m5board.com)

M5Ranger · 22nd July 2007, 23:48

I run the 255/35/20 and 285/30/20 set-up which is almost exactly the same as the stock set-up rolling diameters in 19's. I have seen members run the 305/25/20 set-up but that is almost a full inch shorter rolling diameter. Are there any warning lights going off on the dash ( like ABS etc.. ). I'm not concerned with rubbing, I can deal with that. Wheel people have told me this would not be a good idea, yet I've seen board members running this set-up. I want to try it to get the big rear chunk of tire but I'm not sure. Could those running the set-up please respond as to their experience.

JoeCaMotto · 23rd July 2007, 05:43

Hey M5Ranger im running the 275/305 set-up with no problems @ all, just a litle rub on the rear tires.

MRichmond · 23rd July 2007, 05:51

As I recently described, I am using 265/30/19s on the track, which has a diameter more than an inch less than stock. The only issue is a speedometer error. I can't say whether there are any DSC problems since I turn DSC off on the track.

JamesInLV · 23rd July 2007, 08:40

M5Ranger, I've been running the 305/25 275/30 combo for at least 7000 miles now with no problems. The key is keeping the front to rear ratio approximately the same as stock, which this combo does. On mine with ContiSportContact 3 rears (and CSC 2 fronts), the rolling diameter is 0.9" smaller according to TireRack's site. That is appreciable, but it's never caused a single problem yet. In fact, the slightly smaller diameter delivers a small boost in torque to the ground. Might not actually produce any faster numbers but you can feel it a little.

As MRichmond said, he ran 265/35 all the way around and did just fine. Since the front to rear ratio there is definitely not stock, if any problems with ABS or the DSC system were going to pop up, he would have had them....and he didn't.

M5Ranger · 23rd July 2007, 16:30

Thanks for the input and personal experience. As soon as these PS2's wear out I'm going for it. It should only take a few more launchs (haha). Oh I love your plate JoeCaMotto and the mesh design on your wheels. Are they one piece forged wheels ? Also MRichmond for the track Michelin has the Cup tire ( treadwear 80 ) in 305/30/19 which you could use with 265/30/19 fronts.

JoeCaMotto · 24th July 2007, 01:50

Quote:

Originally Posted by M5Ranger

Thanks for the input and personal experience. As soon as these PS2's wear out I'm going for it. It should only take a few more launchs (haha). Oh I love your plate JoeCaMotto and the mesh design on your wheels. Are they one piece forged wheels ? Also MRichmond for the track Michelin has the Cup tire ( treadwear 80 ) in 305/30/19 which you could use with 265/30/19 fronts.

Thanks, yes they are 1ps froged made by Champion RG41's per Chuck's specs. The Contis are ok tires, but i will up grade to Yoko's next spring. ps i run 275front & 305rear's.

M5Ranger · 24th July 2007, 14:47

I'm an HRE guy but that Champion RG41 is a beautiful wheel I must say. The mesh design is classic and must be very light ( ? weight ). I know the Champion product excellent,strong and light.

JamesInLV · 24th July 2007, 17:45

Quote:

Originally Posted by M5Ranger

I'm an HRE guy but that Champion RG41 is a beautiful wheel I must say. The mesh design is classic and must be very light ( ? weight ). I know the Champion product excellent,strong and light.

I believe the weights came out at 21 pounds for the front and 22 pounds for the rear. I had two of mine repaired, and the guys couldn't believe how light the things were for their size (they deal in a lot of 20-22" wheels for
SUVs too).

deknight · 24th July 2007, 17:59

Quote:

Originally Posted by JamesInLV

...The key is keeping the front to rear ratio approximately the same as stock, which this combo does. On mine with ContiSportContact 3 rears (and CSC 2 fronts), the rolling diameter is 0.9" smaller according to TireRack's site. That is appreciable, but it's never caused a single problem yet. In fact, the slightly smaller diameter delivers a small boost in torque to the ground. Might not actually produce any faster numbers but you can feel it a little...

James I always thought it was the other way around. A larger rolling diameter produces more torque. I run 255/30-20 and 295/25-20 which is 26" rolling diameter I want to go 255/35-20 and 295/30-20 which is 27" rolling diameter same as stock, but no one makes a 295/30-20 except Pirelli P-zero and that is in the near future. So I am thinking of going with 285/30-20 Michelin PS2's since the PS2's have such great traction. I am leary of the Pirelli and have never used them before.