Experiences with 275's on the street? - The Unofficial BMW M5 Messageboard (m5board.com)

Close Encounter · 25th March 2007, 22:45

I know alot of you guys track your cars and use 275's, but do you use them on the street as well? Or do you guys switch over to 245's? This is only a concern to me because we have no tracks up here at all and some of our roads are rutted and I worry about tramlining with 275's.

Any info appreciated, I've done a search and I consistently find nothing but good things said about 275's, but most of them seem to be track oriented only.

MCarRacr07 · 25th March 2007, 23:16

Quote:

Originally Posted by Close Encounter

I know alot of you guys track your cars and use 275's, but do you use them on the street as well? Or do you guys switch over to 245's? This is only a concern to me because we have no tracks up here at all and some of our roads are rutted and I worry about tramlining with 275's.

Any info appreciated, I've done a search and I consistently find nothing but good things said about 275's, but most of them seem to be track oriented only.

I live in NY and our roads are no bargains.....I have 275's all around and no issues...ride is a little firmer but that is more to the suspension.
Go for it!
"M"

Lscman · 25th March 2007, 23:27

Quote:

Originally Posted by Close Encounter

I know alot of you guys track your cars and use 275's, but do you use them on the street as well? Or do you guys switch over to 245's? This is only a concern to me because we have no tracks up here at all and some of our roads are rutted and I worry about tramlining with 275's.

Any info appreciated, I've done a search and I consistently find nothing but good things said about 275's, but most of them seem to be track oriented only.

Some owners drive M5 real hard on the street. They quickly discover that the car understeers hard at the limit...the front tires are too small and become overworked. These folks generally see serious outside treadwear on the front tires too. The 275 on 9.5 upgrade addresses these issues.

If you are not driving hard and experiencing this symptom, then the oversize front wheel will provide no significant benefit. The wider steamroller tires increase tramlining and also make the steering a bit less sensitive. This oversize wheel/tire benefits folks who are grinding their tires at max G's...street or track. The synmptom becomes more pronounced on track because sustained high G's causes the smaller tires to overheat.

ard · 26th March 2007, 01:01

Quote:

Originally Posted by Lscman

Some owners drive M5 real hard on the street. They quickly discover that the car understeers hard at the limit...the front tires are too small and become overworked. These folks generally see serious outside treadwear on the front tires too. The 275 on 9.5 upgrade addresses these issues.

If you are not driving hard and experiencing this symptom, then the oversize front wheel will provide no significant benefit. The wider steamroller tires increase tramlining and also make the steering a bit less sensitive. This oversize wheel/tire benefits folks who are grinding their tires at max G's...street or track. The synmptom becomes more pronounced on track because sustained high G's causes the smaller tires to overheat.

Dang, Not a word to add.

I run 275s up front and haven't tracked. 80% highway, 20% secondardy gravel chip seal roads. Better wear, more sure handling at the limits...

PCUT · 26th March 2007, 01:08

So what toe-in do you run with your 275s? I was thinking of going with 0 degrees but am worried that the tramlining will be exaggerated. I want 0 degrees so I can change the camber for the track and back without destroying the tires. Any thoughts?

Need4Spd · 26th March 2007, 01:14

0 toe is recommended anyway.

The only thing I'll add is that "some" M5s don't tolerate 275s up front w/o some occasional fender rub. My car, for example. Dunno why. After I lowered my car I went back to 245s.

gsfent · 26th March 2007, 01:26

275 all the time. With new thrust arm bushings, I don't have any tramlining. But before I replaced them, the wider tires were much more sensitive to it. So think of 275's up front as your early warning system that the thrust arm bushings are on the way out!

Regards,
Jerry

CSBM5 · 26th March 2007, 03:04

I run 9.5"/275's up front all the time also (have an extra set for track). The car feels so much better, is more balanced, and you can rotate the tires to even out the much faster wearing rear tires. I have no tramlining issues at all. I even did this same mod on my ZHP by putting 8.5"/255's up front -- perfect mod for that car also.

JEM · 26th March 2007, 05:49

Quote:

Originally Posted by gsfent

275 all the time. With new thrust arm bushings, I don't have any tramlining. But before I replaced them, the wider tires were much more sensitive to it. So think of 275's up front as your early warning system that the thrust arm bushings are on the way out!

FWIW I just swapped to 275s all around, I knew my thrust arm bushings were weak and it still feels that way; not a lot of tramlining, just mushy on-center. My wife's '98 540i went through the same aging process, and the X5 bushings brought things back to better-than-new.

I've got a set of X5 bushings sitting here just waiting for the appropriate round tuits.

Part of the reason I went to 275s was that at the same time I do the bushings I'm also pulling out the Dinan stage 3 suspension and going back to stock. I've decided there's elements to the ride quality (a kind of jiggliness in the rear suspension in particular) I don't like.

Having 275s all around ought to deal with the understeer issues in the stock suspension tuning. Otherwise, the only thing I don't like about the stock setup (even in track use) is a slight lack of rebound damping in front, and while the M5 may still see a track event or two a year, mainly I want to focus my track efforts on getting my caged '89 Mustang sorted out.

I guess I'm just getting old.

Lscman · 26th March 2007, 06:26

One solution to front tire rub with 275's is to switch to Ground Control Camber plates and run lots of neg camber. An extra degree of neg camber pushes the top of the tire inward toward the motor almost 1", so this adds more tire clearance at the fender lip. The GC plates give more clearance than Dinan fixed plates. Both setups raise the nose about 3/8" for a given spring.

The extra neg camber will be good for folks who thrash their car around and chew outside tread off their tires. The tires will wear better and the added neg camber will reduce understeer.

The extra neg camber will be bad for conservative drivers who don't do lots of high lateral G's because they will see too much inside tread wear and tramlining may increase. You need to assess how you drive and decide accordingly.