235/45R17 on E36 Coupe

[jom 96]

Has anyone run these on the front? Do they fit OK?

Jo

[kiwi535 538]

i have a couple of well worn examples if you want to try them

[BM WORLD 1264]

should be 235/40-17" for e36 or 225/45-17"

[kiwi328i 118]

Has anyone run these on the front? Do they fit OK?

Jo

I have driven my mates coupe and they fit, but sh*t they are a tight squeeze, without knowing your offsets, its hard to say, have a guess to where your current size tyres are at and go from there. They are half a size bigger than you want really. Of all the sizes I have run on, 205/55-16, 225/50-16, 245/50-16 (on the back), 215/45-17, 235/45-17, 235/40-17, 225/45-17, 245/40-17, 225/40-18's in every combo you can imagine, I now run 245/40-17's all around on my 328i and its the best for me so far.

[sweetm3 180]

I run R888 235/45R17 on my BBS 17X8 ET38 track rims with 10mm spacers, great setup for the track fine for the trip to and from the track.

If you don’t need the spacers then they should work on the road.

But if you need to run spacers and you hit a bump/vehicle crossing the wrong way then you’ll be in for some front fender panel beating. It happened to me for peace of mind I would go with Brent’s suggestions.

[jom 96]

As per Brents comment 235/45 is too tall correct sizes are: 225 /45 or 235/40

I'm running 225/45R17s on 7.5in M3 staggers at the moment on the front, 235/40R17 is slightly smaller and I really don't want to lose any more front ride height. That's why I was looking at the 235/45R17. Apart from that, it's available in Bridgestone RE001 (and the 235/40 isn't) and I rather like RE001s.

Ride height is 40mm down on (stiff) koni sport springs. the 235/40 profile is 7mm smaller radius than the 225/45, the 235/45 is 4mm bigger.

I'm looking to dial out some understeer.

So I guess I'll just have to try them for size.

Paul, I might take you up on your offer....

Thanks everyone for your help.

Jo

[sweetm3 180]

I dailed out a lot of understeer on my car by going square up front (adding spacers) when I was running

8.5in rear and 7.5in fronts.

I changed to 8in rims all round for street use because of my brake upgrade but I stayed with 225/45R17s

up front after the damage I did when I used my race rims and tyres for a week while my extra set of rims were being painted.

Jo just add 10mm spacers up front and stay with your 225/45R17s on 7.5in rims

[jom 96]

If your problem is underesteer then deal with the source of the understeer rather than trying to mask it by tyre size.

Running M3 staggers does slightly increase " traction loss" understeer at the limit it. BUT does not set the car up with understeer across the driving range.

Your source of "understeer" is more likely to be a front roll centre that is too low combined with stiff front springing and probably a stiff front roll bar so the front is doing too much work to control the car resulting in understeer.

What is the car and how is it currently set up and what are you using it for?

It's a stock 97 328i auto Coupe except...

Koni sport suspension - springs and dampers (set to full soft). Springs are supposedly 40 mm drop at the front, 25mm at the rear.

Front crossbrace

Tyres are Bridgestone RE001, 225/45R17 and 245/40R17 on M3 rims

Rear damper mounts are E46 M3

It's a daily driver which goes to Manfield sprints 6 times a year. It's important to keep it comfortable on the road, but also balanced on the track.

One other thought is to change the tyres to 235/40 all round - was this the early M3 setup?

[kiwi535 538]

It's a stock 97 328i auto Coupe except...

Koni sport suspension - springs and dampers (set to full soft). Springs are supposedly 40 mm drop at the front, 25mm at the rear.

Front crossbrace

Tyres are Bridgestone RE001, 225/45R17 and 245/40R17 on M3 rims

Rear damper mounts are E46 M3

It's a daily driver which goes to Manfield sprints 6 times a year. It's important to keep it comfortable on the road, but also balanced on the track.

One other thought is to change the tyres to 235/40 all round - was this the early M3 setup?

are you around over xmas?i can bring the tyres out to you,currently mounted on 17x8 et 20 ex my 535

[jom 96]

are you around over xmas?i can bring the tyres out to you,currently mounted on 17x8 et 20 ex my 535

Thanks for the offer Paul, I'm being led down a different path at the moment....I'll keep it in mind.

[jom 96]

So your car and use is similar to mine except mine is a manual.

I have:

Koni sport adjustables all rounds set to 40% on the front and 30% on the rear

Sports springs all round 20mm lower in the front and 10 mm lower in the rear

M3 sway bars front and rear ( full M3 set up on the front)

M3 top mounts and offset bushes in front suspension.

I ahve 15mm rake (front lower)

I started off on stock 235/40 17s all round and wondered why the arse wiggled every time I punted it through corners- fitted the staggered wheel set up and changed my driving style and picked up 10 to 15kmh through the same corners.

Point 1 - stay with the staggered set up it works really well on a 328

Check your ride height by measuring from the lowest point on the rim to the highest point on the guard.

From what you describe the front is too low compared to the back, set up like this your car will sledge into corners.

Basically if the description is correct , the front roll centre is low and the back is high and the chassis overly raked; when you come into a corner all the weight movement is being controlled through the front axle. So the front tyres, the outer in particular are loading up to control body roll. The back is so high ( relatively) it is not contributing much stability.

Options

The best (road) option is to lift the front 20 mm to let it work properly - this will reduce the induced roll stiffness plus allow the back to work more with the front and provide a better balanced car that drives well on the road and is good for ocasional track days.

If you want to keep the car low but get it handling as well; then drop the back 10 to 15mm and lift the front 5 to 10 mm. This will be better on the track but a but harsher on the road as you will have to drive the corners more to avoid loading the front end up.

Give me the ride height figures and I will give you more accurate details

Ride heights (mm) with 25l fuel, no driver:

FL 557

FR 552

RL 557

RR 550

[jom 96]

Okay:

M3 ride height on staggered 17s factory specs are: 540 in the rear and 585 in the front (Std M3), the sport option lowers the front to 560mm

So when in the most raked mode (sport), the front still measures 20mm higher than the rear (shape of guards)

(I run 560 in the rear and 580 in the front (any lower in the front and I can not get up my driveway) same as the M3 sport set up in rake. I run more rebound control to offset the slight height increase.)

YOURS:

Compared to the std M3 , yours is higher in the back by 7-10 mm and lower in the front by 28 to 33 mm or so you have significantly more rake and a low front roll centre.

Compared to the more raked sport version you still have more rake and you have a lower front roll centre but a significantly higher rear roll centre.

This will make the car sledge in the front as the low roll centre tries to dig in and wave its arse about as the back end jacks up .

Suggestion:

1) Check the spring pads in the front they come in 3mm and 9mm thickness - if thin ones are fitted buy new thick ones, (about $30 each) these were designed to facilitate equalising ride heights but the can also be used for fine height adjustments. Objective: get the front up a bit and even.

2) Fit lower rear springs; M3 ones fit straight in, 328 sport ones are 560mm - you want to go to 540mm.

Objective: Set rake to match the M3 Sport - also even up heights using selected pads.

3) You will then be able to dial in some rebound control which will stabilise the car without making it understeer as the balance will result in the full chassis doing the work not just the front axle - then the rebound will control the un-weighted outside wheel as it is supposed to.

This will give to an extremely neutral handling car that stays neutral, right up till your testicles start shrinking and looking for somewhere to hide.

Just checking the maths (I'm confused)

If I want to go to M3 sport spec, do I need to raise the front from 552/557 to 560? A 9mm spring pad on one side would nearly fix that.

At the rear, I need to swap the springs. To get to a 540 mm ride height can I use M3 springs?

As far as the height at the front, it clears my driveway (not sure by how much, but it does). I'm very interested in the height as I've just fitted new wheelarch liners and underspoiler lumpy bits. Incidentally if you keep breaking the central lower air scoop that's screwed to the body, I have a mod that uses the old broken part and stops it from breaking every time it grounds. The last time it fell off was because running over Manfield kerbs vibrated a screw out and dropped it onto the kerb....and it's still usable.

I know about the shrinking thing. Trying to go flat from the exit of the first corner to the esses at Manfield has a effect not only on the testes, but my right leg also shrinks involuntarily.

[jom 96]

Yes: front up a bit and even and back down; the most important thing is to get the back down so the relative roll centre heights are closer.

If you can't lift the front, just make sure it is even.

Do you have stock sway bars or M-Sport? going bigger on the back helps

The sway bars are standard coupe, so M-sport. I've thought about a bigger bar at the rear, but I think I need to get the ride height down first.

Getting info on springs isn't easy. When I got the car it had Sachs suspension with tapered wire springs, which made for a bouncy (and underbody shattering ) ride, and lousy turn in. Ride heights were about the same as now. I bought the Koni kit thinking that they would base the spring rates and heights on a known reference (eg a BMW OEM set - Avus, rally or something) but I've got the same nose down attitude as the first set. Aftermarket springs too, advertise "25mm lower" etc., but compared to what? Standard, Msport....

Any suggestions?

Cheers

Jo

[jom 96]

you are right get the ride height sorted first then measure the rear bar 18 is sport bar 16 is stock I run a 20

Just to complete the picture:

I dropped the rear 20mm with slightly softer springs. At Manfield today that was about a second a lap quicker. The run in to the esses from Toyota is now flat, before it was "involuntary lift".

Thanks for the help, Ron.

PS rear bar is next.....

[bmpower 3]

Which e36 were you in Jo? The silver one? I was in the white S13 Silvia yesterday - previously i used my burgundy E30 325i.

What times did you get yesterday? Considering the weather and track condition yesterday (wet/damp) - 1sec quicker than normal is much better!

[E30-323ti 66]

I know about the shrinking thing. Trying to go flat from the exit of the first corner to the esses at Manfield has a effect not only on the testes, but my right leg also shrinks involuntarily.

:lol:

Had a decent 'code brown' through that long right hander last trackday I went to.

The E30 runs flat through there (3rd & 4th gear) until the rear tyres get a bit hot, then it's an odd view out the passengers window...

That and spending some time with an instructor on single apex-ing Dunlop.

Right leg starts to spasm wanting to get off the gas

Instructor: keep your foot up it

Driver: Faaaarrrrkkkk I wish this thing was slooooow

[sp8s 1]

Has anyone run these on the front? Do they fit OK?

Jo

I run these on my compact - standard M-Spec suspension - with no problems.

I know they are a half size too big but they hang on great with no understeer on road use, yes I am a pretty spirited driver even in a 2 litre car. using Altenzo's from Jonno and have not found the breaking point yet even in the wet.

[jom 96]

How did the car feel balance wise ?

less understeer, not perfect yet, but it was VERY oily out there. Now at the point where the standard seat belt isn't good enough in the corners, I need a 4 point as my shoulders are sliding off the seat. So an increase in overall grip!

[jom 96]

Which e36 were you in Jo? The silver one? I was in the white S13 Silvia yesterday - previously i used my burgundy E30 325i.

What times did you get yesterday? Considering the weather and track condition yesterday (wet/damp) - 1sec quicker than normal is much better!

average times were about a second better - I'm doing 1.31s instead of 1.32s. Also did my fastest time ever - a 1.30.03. So close to breaking the 1.30 barrier!

I was in the silver 328 coupe (auto...) number 328

Did you go out in the wet? Rain tyres weren't enough, you needed oil tyres. 3 secs a lap slower than a normal wet track, and totally unpredictable.

Edited April 20, 2011 by Jo M

[bmpower 3]

average times were about a second better - I'm doing 1.31s instead of 1.32s. Also did my fastest time ever - a 1.30.03. So close to breaking the 1.30 barrier!

I was in the silver 328 coupe (auto...) number 328

Did you go out in the wet? Rain tyres weren't enough, you needed oil tyres. 3 secs a lap slower than a normal wet track, and totally unpredictable.

You should easily crack the 1.30 mark in the dry then!

Yea i did 5 runs in total - the last one was serious fun, in pouring rain, my window wipers couldn't keep up at 200ish kph down the back straight! I was on semi slicks, great fun! Best run was 1.21.61 for me.