Maximum Wheel Widths

[WISE9UY]

Hello All,

I am deciding on the wheels for my car and now have a number of choices. There have been other threads inquiring about the wheels to run and I now have my view on the limits. By limit I refer to the rim alignment with the edge of the wheel arches with the suspension loaded.

For the front, I have found the limit to be 8" wide with an offset of positive 20. The ET20 clears the leg of the strut by about 5mm.

For the rear, I believe it is possible to run 10" wide with and ET10. I state this because I have put a 9" RC91 on the rear and there is still close to an inch space. By decreasing the offset to 10 to bring the wheel out further and increasing the width by an inch, I think the face would be near in line with the edge.

While I have an RC91 barrel, I have RC90 faces to decrease the offset marginally. I attach a photo of the result at the rear. Tomorrow I will install the front and take a picture of that too.

I recognize that running excessively wide tires at the rear would change the balance of the car and likely substantially increase understeer. Secondly, it is also clear that the double inner fender metal would limit the amount of rolling the lip to allow a wheel to be run so far out, but I believe with a narrower tire it should be possible. Looking at Christian Heine's E9 on it appears possible to successfully run a more aggressive stance.

 

[Randy]

using the trunk as a shelf, for SHAME !!!! What do you have on the Roof! LOL

 

[Markos]

Wise9uy,

It looks like you have a little too much droop in your suspension for an accurate measurement. I think every millimeter counts when you are stuffing the arches with big wheels. I measured 34cm from the center of my hub to the fender arch on my project car (you can see the wheel gap in my profile pic). I measured my rear the other day and set my suspension at 38cm. I ran out of room so I picked up a bottle jack at HF the other day to help cycle the trailing arms. I'm going to remeasure at 34 cm then bump it up more until I'm at no wheel gap and see how the clearance changes. With my WEDS faces installed at 38cm ride height, I had 3.3" of clearance to the outer fender lip, or about 3" to the inner, and 7.2" from the coil spring to the wheel face. Now I know that a member is running 3.5" lips on his custom widened WEDS without rolling the fenders, which leads me to believe that I need to remeasure with the suspension compressed more. BarryG is running 4.5" BBS RS lips on his 10" wheels, with rolled fenders and a very low suspension.

 

[teahead]

I hear 9" in the max wheel size you can fit back there and that probably DOES include rolling the fenders.

 

[Rek]

I have rolled fenders front and rear. 8" on the front and 9.5" on the rear. Both 17" Alpinas.

I can't tell you how it runs on the road as the resto isn't finished and the front and rear rides too high and needs camber plates fitted.

Rears look like the attached.

 

[teahead]

I have rolled fenders front and rear. 8" on the front and 9.5" on the rear. Both 17" Alpinas.

I can't tell you how it runs on the road as the resto isn't finished and the front and rear rides too high and needs camber plates fitted.

Rears look like the attached.

Right. Once you lower it, you may find a rude awakening in the form of massive rubbing.

 

[Markos]

Right. Once you lower it, you may find a rude awakening in the form of massive rubbing.

Surely you can speculate but many people run 17x8 up front with no rubbing, and 9.5's will fit in the rear. If you look at my measurements above there is nearly 11" of fender clearance in the rear Also, lowering the car creates more negative camber and generally helps one fit larger wheels.

 

[WISE9UY]

Thanks for the feedback all. Markos, I agree that there must be a fair amount of drop in my springs as they still look original. Thank-you also for taking some comparative measures. I take it that you loaded the suspension to normal ride level for those measures. I lowered my car down to level to take mine. I am yet to take more as I had suggested as I did not get my wheels back from the refinisher.

As far as considerations of height go, the drop won't affect measure as the geometry of travel will be the same and the spring determines the static position and the rate of travel under load... just stating the obvious . I will be interested to see how it all shapes up once I get my Ground Control setup.

With regards to the feedback on rim widths, I think the warning of rub beyond 9.5" is fair by teahead. While we can roll the edges of the arches, I tend to agree the from of the arch will lead to rubbing with a rim that is in line with the edge of the wheel arch lip. Running a wheel in line with the edge of fender would need an alteration of geometry in my opinion and is likely how others have run 10" wide at the rear.

When I get my other wheels back from refurbishment I will add some more pics.

 

[WISE9UY]

using the trunk as a shelf, for SHAME !!!! What do you have on the Roof! LOL

Wow... your third post on the forum. Welcome! Thank-you for your constructive and valuable input to my thread. If you have any concerns as to why I have something on my trunklid, please feel free to send me a PM LOL

 

[Rek]

Right. Once you lower it, you may find a rude awakening in the form of massive rubbing.

A rude awakening is quite possible as I obviously purchased the new Alpina wheels new at over $500 each because I liked the colour and didn't do ANY research before I put them on such as computer modelling and checking with other members.

Any awakening is better than staying asleep eh?

( Please explain this to anyone for whom irony is a closed book, or a description of a metal object)

 

['69 2800cs]

For reference my ride height is 31.3mm from the wheel lip to the wheel center sitting on the ground. I also measured camber at that height, 3.2 degrees negative.

There is a significant amount of negative camber gain as the wheels go through their travel, at droop camber even goes a bit positive. Negative camber at low ride heights and using a slightly narrow tire is how these larger rims can be fitted.

 

[Markos]

Wise9uy,

My ride height at that measurement was 38cm. My project car is 34cm with plenty of wheel gap. I'm going to try again this weekend and do 32cm and 34cm.

 

[WISE9UY]

Wise9uy,

My ride height at that measurement was 38cm. My project car is 34cm with plenty of wheel gap. I'm going to try again this weekend and do 32cm and 34cm.

Hi Markos, my ride height is 365 on the driver side and 355 on the passenger. I wonder if that difference is to allow for a driver to be in the car. But in any case, averaged out at 360mm is right between both your cars.

Here is a question to the group, what is the ride height running the Carl Nelson/La Jolla Springs?

 

[nathanegger]

Did the bolt pattern match?


Sent from my iPhone using Tapatalk

 

[WISE9UY]

Did the bolt pattern match?

Sent from my iPhone using Tapatalk

Which bolt pattern are you referring to? BMW stud is all 5 x 120 in the modern era with varying offsets.

 

[floridabmx]

18x8.5 [emoji54]

 

[Markos]

Very nice!

My whole measurement thing has taken a back seat to parting my CSI. Finally getting back on the horse...

 

[WISE9UY]

18x8.5 [emoji54]

Those RS's with stepped sizing look great! What is the offset on these? Also, did you happen to load the suspension and measure the gap from the fender's edge to the edge of the wheel?

 

[Gransin]

Here is some information I got from a person who had a very low and stanced e9 before, I asked him directly many years ago when my plan still was to go with big wheels.

"The BBS were 18x8.5 et13 and 18x9.5 et13.
In the rear, you cannot fit a wider wheel, nor a 9.5 in any other offset. It clears both the inside and outside of the fender by about 1mm.
When I swapped to the HREs, I went with 18x8 et10 and 18x9 et10 for a little extra room, and I was glad I did. Those are the sizes I recommend if you're going for that look"

Cheers,

 

[WISE9UY]

For more information in this thread, I also test fitted the 8x17 ET20 BBS RC090 to get a measure on that compared to the 9" I had tried on at the start of the thread. As expected the 8" is essentially half an inch deeper inside the fender lip than the 9", where the similar ET on both distributes the extra width evenly between the inside and outside of the wheel well. On this basis, I believe without issue it is possible to run 9.5" rims on these cars with the right offset.