8.5 all round on E36 m3

[sweetm3 180]

Hi Guys

I'm looking at buying a set of rims just for track days. 8.5 all round this would replace my staggered set up 7.5 F 8.5 R on my E36 m3.

There is a set on trademe with an offset of 44 could i get away with it (standard m3 offset 41) ? any other problems

Thanks

[E30-323ti 66]

Hi Guys

I'm looking at buying a set of rims just for track days. 8.5 all round this would replace my staggered set up 7.5 F 8.5 R on my E36 m3.

There is a set on trademe with an offset of 44 could i get away with it (standard m3 offset 41) ? any other problems

Thanks

You are running coilovers aren't you???

If so, 8.5" wheels will need spacers up front, I run 15mm spacers with my 8.5" et40 wheels, I think 10mm would work but I need bigger for caliper clearance.

Also depends on your front spring length, as to were the collars/tyre sit.

[sweetm3 180]

Thanks for the reply, yes I do have coilovers.

I found a wheel offset calculcator

This is what it came up with

Front inner clearance 16mm less, outer extended 10mm.

Rear inner clearance 3mm less, outer retracted 3mm

I think I'll put a question in the race tec and see if any of the guys racing E36s think its worth

going with the 8.5 or not

[E30-323ti 66]

Thanks for the reply, yes I do have coilovers.

I found a wheel offset calculcator

This is what it came up with

Front inner clearance 16mm less, outer extended 10mm.

Rear inner clearance 3mm less, outer retracted 3mm

I think I'll put a question in the race tec and see if any of the guys racing E36s think its worth

going with the 8.5 or not

The rears will fit fine obviously.

The fronts coming in 16mm will be into the spring unless you have 'shorties' (5" springs) and the perch/collars are high enough.

Being able to run a 'square' setup would be the advantage over the staggered (both in handling & tyre rotation).

Whether it's an 8" or 8.5" setup would be the question. (7.5" is a bit weedy for a tubby E36).

A 255/40 fits a 8.5" OK but is ballooned on a 8" and best on a 9", it will also likely rub on the E36 without some guard rolling.

The other size would be a 235/40 (or 45) which is fine on a 8" or 8.5" and won't rub.

But is that enough tyre for you?? It's what I run at the track (D01J's on 8") but a couple hundy kg less and bit more power.

[CamB 48]

Or alternatively, run same size tyres front and rear like the guys who race them, and tune your suspension accordingly, if needed. Based on driving mine (staggered), I reckon I'd want same size front/rear at the track.

Non-Evo M3's often/usually had staggered wheels with same size tyres front/rear - there is nothing wrong with staggered wheels/same size tyres other than the inconvenience of not being able to easily swap tyres front to rear.

Personally for a track/race car I would track down a set of 17x7.5s with the correct offset, and as light/strong as possible.

[westy 614]

I prefer a square setup than a staggered one also.

[CamB 48]

Non-Evo M3 came with same size front and rear - I don't see the problem.

I do see the guys racing using same size - possibly because they're cheap (although racers with M3s usually aren't). Possibly because it handles better.

[CamB 48]

Look, I'm not sure I can say this without it coming across aggressively, but find me an E36 racer using a staggered setup and I'll believe you. None of the guys racing here do that I am aware of. I'm pretty sure the factory race cars don't either (not that that is particularly relevant given how far away they are from street cars).

I can see you've driven both and formed an opinion on this basis, but my observation is that you're a minority with this view.

I think my point is that grip - both ends - would be maximised by having a balanced setup.

[E30-323ti 66]

Look, I'm not sure I can say this without it coming across aggressively, but find me an E36 racer using a staggered setup and I'll believe you. None of the guys racing here do that I am aware of. I'm pretty sure the factory race cars don't either (not that that is particularly relevant given how far away they are from street cars).

I can see you've driven both and formed an opinion on this basis, but my observation is that you're a minority with this view.

I think my point is that grip - both ends - would be maximised by having a balanced setup.

Well said, other than the "factory" race cars, as that is a bit open, in terms of 'super tourer/BTCC' Vs the 'M3 GTR's' of the E36 variety which not only run staggered widths but heights also.

With race tyres costing substantially more than most/all road tyres, the ability & intern flexibility of being able to swap tyres around to cater for wear & damage etc... far out weigh any real or perceived gain by running a staggered setup for 95% of E36 racecar owners.

Also given the E36 poor camber curve & shocking roll characteristics of the front end (esp. low racecars) the wider/balanced front tyres will get plenty of excercise & be well worth it.

If you've got the coin to throw around running different width/diameter/compound race tyres (let alone the rest of the setup) to suit the track,weather etc... then go for gold.

[chase 0]

"Look, I'm not sure I can say this without it coming across aggressively, but find me an E36 racer using a staggered setup and I'll believe you. None of the guys racing here do that I am aware of. I'm pretty sure the factory race cars don't either (not that that is particularly relevant given how far away they are from street cars)."

Well..... I run a staggered set up on my 3L M3 carspot#59 in the open class 235-45X17 front on 7.5 and 255-40X17 on 8.5 Toyo R888 rear not sure if that counts ,my car came with these wheels standard, had to roll and beat the guards both front and rear, rear is still real close, running koni 2 way adjustable shocks and bigger front sway bar best time Puke 1.08.49 best race result 2nd and round result 3rd in the Jan meeting last year I'm pretty sure I was the first car not running slicks in both races except handicap races so the staggered set up works well in my view, but ...... it is always going to be a bit trickier to set up as always you pays your money and takes your choice the bonus with the 255 rears is it looks real cool !!

Plus the price of the tyres was very reasonable !!

If you want to talk more about how to set up feel free to give me a call 0275 924 817

Bugger posted with my sons account again, bloody auto login

chhers 10hove

Edited September 5, 2008 by Chase.t

[CamB 48]

Well I'm happy to agree if the well-funded race guys (those who can test and choose) choose the staggered setup then it must be better. It's not like I've tried it myself.

It is definitely possible that most of the cars I've looked at/read about are restricted by rules.

(to defend myself, I still think I'd run same front/rear, for several reasons already discussed).

Edited September 5, 2008 by CamB

[sweetm3 180]

Guys thanks for your input, I will give Alex a ring.

[E30-323ti 66]

The logic of the comments about the suspension geometry (323ti) are totally contradictory and incorrect a wider (low profile) tyre is worse in this situation as the contact patch will move from the outside to the inside as the suspension compresses and the other way as it expands so:

The contact patch should not move from one side to the other, that would mean the camber has gone from +ve to -ve.

Which may well happen in a road car with low static camber, but E36 racecars generally run in excessive of -3.5d so this does not happen.

As the chassis roll into the corner and the suspension compresses more of the tyres width becomes presented to the road surface elongating the contact patch increasing the lateral grip, this is true no matter the tyre width, and is verified by taking the tyre temp across the width. If the temps are uneven them you have too much or too little camber. A wider tyre will handle temperature better due to the simple fact there is more tyre.

The rate the E36 geometry gains camber under compression is less than the rate it looses it due to the roll characteristics, thus the comparatively high static camber required.

You get the car walking all over the track as the suspension goes up and down. Hence the comment about staying narrower, unless you need the braking and high speed corner stick.

The car will not "walk all over the track" unless you have incorrect toe settings, not tyre width.

Stock is to have the front 'toe-ing in' with low static camber which under compression trends towards toe-out making it feel less stable if you just "chuck some fat tyres on". A proper race/track alignment should have the front with slight toe-out and a lot of camber to eliminate that area of instability during suspension compression.

A car with stock alignment settings will 'tram line" with wide tyres!!

Remember we are talking about a Track car setup here, which to me means "you need the braking and high speed corner stick"

I used to run 235 40 on the front and 255 40 on the rear now running 225 45 front and 245 40 on rear due to changing tyre brand

Thats all well and good for a road car, I used to run the same 225 45 / 245 40 combo, which felt great on the road, but was terrible on the track, esp. Manfield, which cooks front lefts. Switching to 245's all round made a world of difference even on street tyres (now on semi slicks).

SweetM3:

At the end of the day it all come back to $$$.

If you can afford to maintain a staggered setup and are happy with the way it "works" then go for it, as I said earlier.

You're running the GC track/school kit aren't you??

I would be looking to what the majority of the guys in the US are using, I'd bet you will find most are on a square setup on 235 or 255/40 17x8.5" or 9" (which are very cheap for them, lucky buggers)

On a typical track day I take 6 wheels/tyres (all the same), there is nothing worse than flat-spotting a front in the first session and not having the ability to swap front to back (which is easy to do when you have 'moments'), or grab a spare for that side (thus the 2 spares), chances are it will ruin your day, or you continue and not learn anything and destroy a tyre.

[E30-323ti 66]

The contact patch will move from side to side, the distribution of temp is proof of this. - in a straight line with -3.5 the outer edges will not be doing much work, into corners the work moves out across the tyre, it is the body roll that determines this as well as the tyre compression to a lesser degree.

That is true, but as I stated above, the need to have a high static camber to over come the Roll is what gives you even tyre temps.

The tyre width means you have more area / volume for the heat to build up in which reduces the average temperature and yes a wider tyre will present more area and result in a reduction of localised heat. And yes you may have cooked your 225's on the front an manfield but this can be driving style and lack of rubber - wider all round may also have resolved your problem.

I have no doubt driving style played some roll in the problem, but the simple change to matching front & rear widths resolved the issue, moreso than any driver improvement LOL

Excessive -ve camber and toe out can both result in walking all over the track, combining them is a bit old of an school set up, but suits some driving styles and car set ups, I am not a fan of it because it tends to load up front outer wheels.

I find it a lot more stable than moderate camber & stock 'toe-in' especially under brakes.

I run 1/16" toe-out on the front, so not huge, and have plenty of HP/TQ to push it, which is where some run 0 toe and deal with less stability.

P.S. the post starts off with a query about "just for track days" so I assume this is not a purpose built race car.

I run the same wheel set on the road with 0.8 degrees negative; for very ocasional track days I run 2 to 2.5 degrees negative. This works fine with the rest of the suspension ( Koni Sport adjustable and uprated springs all round and complete M3 front suspension set up ) for "just track days".

My car is a 328 which is lighter than an M3 and specifically in the front by about 50kg over the front axle.

It did indeed and we have rambled OT on a suspension geometry session LOL,

Knowing he is running a pretty 'complete' track suspension setup, some small alignment changes the day before will make more difference than a staggered Vs Non-Staggered setup.

I which case, it's best to become familiar with doing his on "string" alignments.

But these are whole other threads by themselves.

Just go with what you can afford, and think through all the possible scenario's that may cost you time & $$$

[CamB 48]

So 3pedals ... thinking aloud - would your car still drive better with a staggered setup AND 50kg over the front wheels, or would that tip the balance (sorry about the pun) towards same size front/rear...