12mm H&R spacers on the rear only

[BeachM5nster]

i've had a full set of spacers setting in the garage for over a month as i couldnt decide if i wanted them at all, and if I did, which ones would I put on the front and which ones would i put on the back.

i searched all threads and read and researched... porsche sells some of their hi-perf cars with spacers, so i was like "ok ill do this"...

but what seems to be most popular and "correct" on our car is larger spacers in the front and smaller spacers in the rear. i've seen maybe one post of pics of 10mm all around. but the 12fr/10rr seems to be whats done the most and has the most photos by far

but my instincts told me i would either want the same size spacer on each wheel to keep it oem ratio, as some guys commented, or that i would want a wider track in the back only. when i saw BMS's advert with 12fr/15rr, i knew a wider rear was the call... the 12/15 looks pretty good but just a lil too froggy i think.

and i have to pat myself on the back, 12mm only on the rear is perfect.
- the rear wheels are flush with the fender, it looks much better.. and after 150 miles i can say that the rear track is only a hair wider and it handles just a hair better. a lil sturdier feeling. nothing negative and no compromise to report


with my research i also found the reason guys do 12front 10 rear or even 15mm front and 12rear is not for performance at all. it is just to be flush with the fenders and the front fenders flare out a bit more than the rear so they push the front wheels out more with larger spacers to be flush in the front, too...

but nobody else has said it, so i will: that is nonsense

it is an example of "not seeing the forest for the trees", - meaning the guys are aiming to be flush with the fender so much so that they forget the rear needs to be the same width or wider as the front, not narrower, for handling. if all wheels are flush with their respective fender, but the front fenders of the car(like our f10m5's) are a bit farther out, you then mess up the wheelbase geometry of the car for the worse to chase a look that ironically ends up skewing the overall look

- Aesthethically a wider track in the back is better and more athletic looking but they betray that fundamental aesthetic for an auxiliary aesthetic and then it has the wheelbase geometry of a forklift

and sticking the fronts wheels out will sling everything up your sides, side mirrors and side windows.. i know that from other cars ive had.

I couldn't find any pics of spacers only on the rear, so enjoy
H&R 12mm rear only. stock suspension non-cp

[FTP20]

Agreed. 12mm on the rear and nothing on the front actually looks quite good. My preferred combo is 10mm rear and 3mm front - clean, classy and perfectly balanced. IMO 15mm spacers on either end look like The Hulk trying to wear a shirt three sizes too small and bursting at the seams. Sometimes more isn't better.

[BeachM5nster]

Originally Posted by FTP20

Agreed. 12mm on the rear and nothing on the front actually looks quite good. My preferred combo is 10mm rear and 3mm front - clean, classy and perfectly balanced. IMO 15mm spacers on either end look like The Hulk trying to wear a shirt three sizes too small and bursting at the seams. Sometimes more isn't better.

i agree. i actually put a 10mm on and it wasnt quite flush. when i get 305's on they might stick out a lil much with 12mm
as far as 3mm on the front, meh, my whole qualm with spacers on the front is just all the movement on the front. the rear is always locked in so i feel its less prone to any spacer issues.

[FTP20]

Originally Posted by BeachM5nster

i agree. i actually put a 10mm on and it wasnt quite flush. when i get 305's on they might stick out a lil much with 12mm
as far as 3mm on the front, meh, my whole qualm with spacers on the front is just all the movement on the front. the rear is always locked in so i feel its less prone to any spacer issues.

Not sure what you mean by "my whole qualm with spacers on the front is just all the movement on the front". With a flat 3mm spacer on the front the wheels still sit centered on the hub so there is no movement. Of course 3mm longer M14x1.25 are required to maintain the correct amount of thread engagement.

I am solidly in the camp that doesn't agree with mounting 305/30R20 tires on the original 10" rear wheels but YMMV... FWIW, the narrowest wheel that Porsche has ever spec'd for this tire size is 11" and their higher performance models use 11.5" and 12" wheels with 305/30R20 tires.

[BeachM5nster]

Originally Posted by FTP20

Not sure what you mean by "my whole qualm with spacers on the front is just all the movement on the front". With a flat 3mm spacer on the front the wheels still sit centered on the hub so there is no movement. Of course 3mm longer M14x1.25 are required to maintain the correct amount of thread engagement.

I am solidly in the camp that doesn't agree with mounting 305/30R20 tires on the original 10" rear wheels but YMMV... FWIW, the narrowest wheel that Porsche has ever spec'd for this tire size is 11" and their higher performance models use 11.5" and 12" wheels with 305/30R20 tires.

all i meant was im just not completely confident about spacers bc theres so many possible negatives reported about them but im not sure you can get a hubcentric spacer at 3mm but either way its small potatoes.

good and valid info on the tires.. im just going on recommendations from other members thst said they grip a lot better but i have no exp or knowledge past other members that have done it. where you at M5theonlyone ?

[M5Rick]

Originally Posted by FTP20

Not sure what you mean by "my whole qualm with spacers on the front is just all the movement on the front". With a flat 3mm spacer on the front the wheels still sit centered on the hub so there is no movement. Of course 3mm longer M14x1.25 are required to maintain the correct amount of thread engagement.

I am solidly in the camp that doesn't agree with mounting 305/30R20 tires on the original 10" rear wheels but YMMV... FWIW, the narrowest wheel that Porsche has ever spec'd for this tire size is 11" and their higher performance models use 11.5" and 12" wheels with 305/30R20 tires.

911's v heavy rear (it is) calls for different specs of wheel/tyre combo, cannot be compared with M5.Applying a wider tyre say 325 on 11's on a 911 would make it too woolly because of the whole slow in fast out nature of the 911.Apples and oranges.

[AirBull]

Originally Posted by FTP20

I am solidly in the camp that doesn't agree with mounting 305/30R20 tires on the original 10" rear wheels but YMMV...

What do you not agree with there? In the new Michelin PS 4S they sound like they offer a lot more traction which would be helpful in the rear.

[BeachM5nster]

Originally Posted by M5theonlyone

911's v heavy rear (it is) calls for different specs of wheel/tyre combo, cannot be compared with M5.Applying a wider tyre say 325 on 11's on a 911 would make it too woolly because of the whole slow in fast out nature of the 911.Apples and oranges.

please go into more detail about the slow in, fast out (i know its taking a corner) but i hear that about porsches.. is that a bad thing? whats the m5 in those regards? fast in, fast out?

and do you have a photo of your 305's?

[FTP20]

Originally Posted by AirBull

What do you not agree with there? In the new Michelin PS 4S they sound like they offer a lot more traction which would be helpful in the rear.

Perhaps more straight line traction but this is mostly down to the improved compound and because people are often replacing worn and heat-cycled tires with fresh rubber.

The specs don't lie!

295/30R20 Pirelli P Zero Star BMW spec
TREAD WIDTH 11.4" (measured on a 10.5" wheel)
APPROVED RIM WIDTH 10" - 11"

295/30R20 Michelin Pilot Super Sport Star BMW spec
TREAD WIDTH 11.6" (measured on a 10.5" wheel)
APPROVED RIM WIDTH 10" - 11"

305/30R20 Michelin Pilot Sport 4S
TREAD WIDTH 11.2". (measured on an 11" wheel)
APPROVED RIM WIDTH 10.5" to 11.5"

Porsche doesn't use min-11" rear wheels due to vehicle weight; the rear of an F10 M5 is heavier than the rear of any 991 variant and it is air pressure inside the tire that supports vehicle weight, not rim width.

[FTP20]

Originally Posted by BeachM5nster

please go into more detail about the slow in, fast out (i know its taking a corner) but i hear that about porsches.. is that a bad thing? whats the m5 in those regards? fast in, fast out?

Start with these books:

Going Faster!: Mastering the Art of Race Driving: The Skip Barber Racing School

Bob Bondurant on High Performance Driving - 5th Edition

[Ickdeep]

It looks good and I see whatcha mean about the "stance" of the car. I personally have 12 fronts and 10 mm rear and the car handles just fine. I've taken it out for a few autocross events and even two skid pads events and car is loving it.

[M5Rick]

Originally Posted by BeachM5nster

please go into more detail about the slow in, fast out (i know its taking a corner) but i hear that about porsches.. is that a bad thing? whats the m5 in those regards? fast in, fast out?

and do you have a photo of your 305's?

Already posted photo in the wheel/tyres section.
The slow in, fast out refers only to a rear drive (even 4wd) 911. Entering a corner too fast and applying throttle too much is a passport to a spin followed by impacts due to loss of control.This is unlikely to be the scenario with a front engined rear drive M5 which would be more forgiving in such circumstances and much less likely to spin with the engine at the opposite end preventing the all too easy spin pendulum effect of a 911.Hope that explains it a bit more.

[BeachM5nster]

Originally Posted by FTP20

Perhaps more straight line traction but this is mostly down to the improved compound and because people are often replacing worn and heat-cycled tires with fresh rubber.

The specs don't lie!

295/30R20 Pirelli P Zero Star BMW spec
TREAD WIDTH 11.4" (measured on a 10.5" wheel)
APPROVED RIM WIDTH 10" - 11"

295/30R20 Michelin Pilot Super Sport Star BMW spec
TREAD WIDTH 11.6" (measured on a 10.5" wheel)
APPROVED RIM WIDTH 10" - 11"

305/30R20 Michelin Pilot Sport 4S
TREAD WIDTH 11.2". (measured on an 11" wheel)
APPROVED RIM WIDTH 10.5" to 11.5"

Porsche doesn't use min-11" rear wheels due to vehicle weight; the rear of an F10 M5 is heavier than the rear of any 991 variant and it is air pressure inside the tire that supports vehicle weight, not rim width.

so the the super sport has a larger contact patch in a 295 than the 4s in a 305? interesting