[JRocker3]

E90 platform FTW

[sirdaft1]

Important discovery we've made during this build pertaining to the max tire widths on the FRONT of the e90. Since most e90's came equipped with a 225 front tire from the factory, it's no surprise to find that there would be fitment issues when running FAR wider than OE spec.

While wide body kits (Hard, WTCC, etc) will remedy the common fender clearance issues... we found that there is a body/firewall limitation that comes into play when you run a 265 or wider wheel package. Our ideal tire up FRONT will be a 295 or 305.

When running a 265 or wider tire up front, it requires either a lower offset wheel or a spacer to push the wheel away from the suspension (rubbing). This push outward increases the radius of the outer part of the wheel, beyond OE spec and causes it to rub parts of the firewall when wheels are turned.

That said, here's a quick reference guide from what we've discovered. This is only for the e90 chassis (sorry can't comment on e92's) and it doesn't take into account width variances between tire manufacturer. This also assumes proper wheel offsets.

E90 Front Tire Widths:
245 or under: No modifications needed
255: Possible fender roll (depending on suspension setup/drop)
265 - 285: Widebody/cut fenders + cut out firewall seam weld
295+: Widebody + extensive modification to firewall

Passenger side front wheel well. Notice the seam weld behind the tire:


Highlighted the rub area in red. Fortunately this part can be removed fairly easily:

[berns]

Originally Posted by sirdaft1

Important discovery we've made during this build pertaining to the max tire widths on the FRONT of the e90. Since most e90's came equipped with a 225 front tire from the factory, it's no surprise to find that there would be fitment issues when running FAR wider than OE spec.

While wide body kits (Hard, WTCC, etc) will remedy the common fender clearance issues... we found that there is a body/firewall limitation that comes into play when you run a 265 or wider wheel package. Our ideal tire up FRONT will be a 295 or 305.

When running a 265 or wider tire up front, it requires either a lower offset wheel or a spacer to push the wheel away from the suspension (rubbing). This push outward increases the radius of the outer part of the wheel, beyond OE spec and causes it to rub parts of the firewall when wheels are turned.

That said, here's a quick reference guide from what we've discovered. This is only for the e90 chassis (sorry can't comment on e92's) and it doesn't take into account width variances between tire manufacturer. This also assumes proper wheel offsets.

E90 Front Tire Widths:
245 or under: No modifications needed
255: Possible fender roll (depending on suspension setup/drop)
265 - 285: Widebody/cut fenders + cut out firewall seam weld
295+: Widebody + extensive modification to firewall

Passenger side front wheel well. Notice the seam weld behind the tire:


Highlighted the rub area in red. Fortunately this part can be removed fairly easily:

I don't think this is necessarily true. I ran a 265/35/18 on an 18x9.5" +25 wheel, with stock front fenders. It just takes proper camber specs and a 7" spring with no helper. If I didn't sell the car, I'm pretty confident I could have run a 275 square with little or no work.

[Tim603]

Originally Posted by berns

I don't think this is necessarily true. I ran a 265/35/18 on an 18x9.5" +25 wheel, with stock front fenders. It just takes proper camber specs and a 7" spring with no helper. If I didn't sell the car, I'm pretty confident I could have run a 275 square with little or no work.

It probably comes down to aspect ratio/circumference more so than width. The larger the sidewall the more chance of hitting the firewall vs a low profile tire like yours clears the firewall no problem even though wide

[feuer]

Originally Posted by berns

I don't think this is necessarily true. I ran a 265/35/18 on an 18x9.5" +25 wheel, with stock front fenders. It just takes proper camber specs and a 7" spring with no helper. If I didn't sell the car, I'm pretty confident I could have run a 275 square with little or no work.
]

Originally Posted by Tim603

It probably comes down to aspect ratio/circumference more so than width. The larger the sidewall the more chance of hitting the firewall vs a low profile tire like yours clears the firewall no problem even though wide

It will depend on wheel offset and caster too, which are probably the
biggest reason sirdaft1 is experiencing this issue. I believe slonik modify the firewall a year ago. I think they cut the corner and welded it back the other way.

[slonik]

Originally Posted by feuer

It will depend on wheel offset and caster too, which are probably the
biggest reason sirdaft1 is experiencing this issue. I believe slonik modify the firewall a year ago. I think they cut the corner and welded it back the other way.

on our e82, yep we've made this.

[sirdaft1]

Originally Posted by slonik

on our e82, yep we've made this.

Can you share any pics?

[slonik]

this is from uploaded pics, which i've posted in our topic.

i can search on pc if you need another.

[sirdaft1]

Originally Posted by slonik

this is from uploaded pics, which i've posted in our topic.

i can search on pc if you need another.

These are excellent. I realize this is an e82 so there are differences from the e9x chassis. What tire width are you running?

[Rain]

I'm wondering about something else - do you really need so width tires infront? For me 295/305 is total overkill which might start perform worse than 265 lets say. Also will be way heavier

[slonik]

Originally Posted by sirdaft1

These are excellent. I realize this is an e82 so there are differences from the e9x chassis. What tire width are you running?

275/35 R18 hankook z214, square setup.

[slonik]

Originally Posted by sirdaft1

These are excellent. I realize this is an e82 so there are differences from the e9x chassis. What tire width are you running?

part number 1 on pic for example, is the same on e9x e8x.
all other parts almost the same.

[sirdaft1]

Originally Posted by berns

I don't think this is necessarily true. I ran a 265/35/18 on an 18x9.5" +25 wheel, with stock front fenders. It just takes proper camber specs and a 7" spring with no helper. If I didn't sell the car, I'm pretty confident I could have run a 275 square with little or no work.

Just a little confused, how would running without a helper allow you to fit more wheel? Upon compression, the spring will take up the same space as the helper spring and cause rub regardless. Correct?

Also, I just see no possible way to squeeze a 275 up front without modification to the fender. I can take photos for you but we have a 275 up front right now and it's hugged as tight as you can comfortably go to the strut and unless you have the suspension setup like a 4x4... you'll get fender rub.

But I digress. The point of my post above is to highlight that there are issues with firewall clearance. Perhaps you can squeeze a 265 with enough caster without needing to modify the firewall seam weld. But the point remains that modification is required at some point with a 265 or wider front tire.

[slonik]

Originally Posted by sirdaft1

Just a little confused, how would running without a helper allow you to fit more wheel? Upon compression, the spring will take up the same space as the helper spring and cause rub regardless. Correct?

Also, I just see no possible way to squeeze a 275 up front without modification to the fender. I can take photos for you but we have a 275 up front right now and it's hugged as tight as you can comfortably go to the strut and unless you have the suspension setup like a 4x4... you'll get fender rub.

But I digress. The point of my post above is to highlight that there are issues with firewall clearance. Perhaps you can squeeze a 265 with enough caster without needing to modify the firewall seam weld. But the point remains that modification is required at some point with a 265 or wider front tire.

we have 1m front arms, kw competition 2way with 3 degrees camber, and et22 9.5 apex ec7 wheels, with 5mm spacer .
no problems on top and rear of the liner, only a little on the front, when some time gone and liner goes back to it's factory form (we are rolled it for more space with heat gun).

[sirdaft1]

Originally Posted by Rain

I'm wondering about something else - do you really need so width tires infront? For me 295/305 is total overkill which might start perform worse than 265 lets say. Also will be way heavier

We're building the wheel package to be able to fit up to a 305 front tire and we may dial it back depending upon results. turb0mik3 runs a 285 Pirelli DH up front and he is shooting at adding a wider tire up front going forward. The e90 is no lightweight unfortunately

But I think the point you are getting at is that wider does not always equate to better, which I couldn't agree with more. The name of the game is getting heat into the tires. A colleague of mine just completed a Mazda MX-5 ND race car build. During testing they found that the car was happier with a slightly skinnier tire up front than they initially planned for as the lightweight chassis didn't put enough heat into the tire.

I'll report back with real world details in the future

[Rain]

Exactly sirdaft1! Good luck it will became great car I'm absolutely sure about it

Looking forward for the report and some video of racing this beast out there hehe

[berns]

Originally Posted by sirdaft1

Just a little confused, how would running without a helper allow you to fit more wheel? Upon compression, the spring will take up the same space as the helper spring and cause rub regardless. Correct?

Also, I just see no possible way to squeeze a 275 up front without modification to the fender. I can take photos for you but we have a 275 up front right now and it's hugged as tight as you can comfortably go to the strut and unless you have the suspension setup like a 4x4... you'll get fender rub.

But I digress. The point of my post above is to highlight that there are issues with firewall clearance. Perhaps you can squeeze a 265 with enough caster without needing to modify the firewall seam weld. But the point remains that modification is required at some point with a 265 or wider front tire.

Wasn't at all trying to take away from your efforts, and I totally understand your goal. My post was more geared to the dudes looking for traction and an aggressive tire setup, and to let them know that it's possible to fit a pretty healthy wheel/tire combo without a ton of modifications.

The lack of a helper, on my setup at least, meant I could run a 7" spring at a good ride height with minimal interference between lower perch and sidewall. 7" plus helper would have made that more difficult.

Carry on, man, and thanks for all the awesome info! Car is going to be awesome.

[sirdaft1]

Originally Posted by berns

Wasn't at all trying to take away from your efforts, and I totally understand your goal. My post was more geared to the dudes looking for traction and an aggressive tire setup, and to let them know that it's possible to fit a pretty healthy wheel/tire combo without a ton of modifications.

The lack of a helper, on my setup at least, meant I could run a 7" spring at a good ride height with minimal interference between lower perch and sidewall. 7" plus helper would have made that more difficult.

Carry on, man, and thanks for all the awesome info! Car is going to be awesome.

Sorry I didn't mean to come in hot on you either! All good brother. I just wanted to make sure I wasn't misunderstanding something.

Now we just need to get you back into a 335 so you can come join on track

[sirdaft1]

Originally Posted by Rain

Exactly sirdaft1! Good luck it will became great car I'm absolutely sure about it

Looking forward for the report and some video of racing this beast out there hehe

Thanks!!

[berns]

Originally Posted by sirdaft1

Sorry I didn't mean to come in hot on you either! All good brother. I just wanted to make sure I wasn't misunderstanding something.

Now we just need to get you back into a 335 so you can come join on track

Ha, all good man!

I left the 335 to do more track stuff in a 135. I missed having two doors and didn't want to achieve 3000lbs by gutting my awesome street car. I learned a lot with my E90 and my E82 will be even better. I'll start a build thread of my own soon. Can't wait to see your project complete!

[sirdaft1]

Paid a quick visit to eFab last night to check in on sleeping beauty. Man, so close to being done with phase 1!! Tonight she did a quick weigh-in she's around 2900lbs with only a handful more parts. We’re confident that without fuel or driver that she’ll tip the scales at just under 3k lbs. Not bad given how heavy she was stock and that we didn’t skimp on cage safety!

A couple of updates and discoveries...

Test fitted some 325 Pirelli slicks in the rear (about 70mm taller than we need, but width is correct to what we plan on running). LOTS of room in the rear to fit this rubber with the HARD Widebody.


305 Pirelli DH slicks for the front. Unfortunately the HARD kit comes nowhere close to fitting this rubber up front.




Still trying to decided whether or not we keep the 328 badge on the trunk lid


Stock non-M strut tower brace does not fit MCS style suspension. The good news is that’s you can swap in the e9x M3 strut tower brace

Stock 335


M3 - beefier and far more shock tower support vs non-M, not to mention it fits around MCS suspension

[JRocker3]

Keep the 328 badge!

Are you planning to keep the car black? Paint? Vinyl wrap?