Widest rear wheel?

[Minivansomeren]

Question: what is the widest rear wheel/tire anybody has run without changing suspension or rolling arches?

Background: I’ve seen several references to the rear track on our cars, which is 42mm narrower than the front. This means that the rear hubs sit almost an inch (21mm) further in-board than the fronts. I assumed this is the reason that people run a staggered tire setup that is wider at the rear. However I recently did the math and the common 8” wide et24 wheels don’t change this at all. Compared to a 7” et11 wheel, the lips on staggered wheels are actually 0.3mm further inboard. In other words, the extra inch on a staggered setup is added on the inside, not the outside. So I guess the main benefit of a staggered setup would be handling (better RWD grip) rather than aesthetics?

My question is whether anybody has tried a staggered setup that adds the extra rear width on the outside, rather than the inside? Theoretically that would be a 16x8 et-2 and it would place the rear wheel lips 4mm further out than the fronts, rather than 21mm further in on the stock setup. I recently got a set of BBS RS005 wheels that need to be refinished, and could achieve this by putting 2.5” lips on the rear, giving it a deep-dish look. I have stock ride height (I think) and would like to avoid rolling fenders.

I’ve done a lot of searching on here and found people running 17x9 et20 wheels in the rear, apparently without rubbing. That wheel would be 16mm further out than stock, but not the full inch. Most other people trying to stuff big wheels in the rear have rolled fenders and lowering springs.

 

[ElGrecko]

It's more likely that the rear track was a leftover from the 2000CS and the front end parts came from the E3. Since they were redesigning everything from the firewall forward when they redid the car that's likely what happened. To widen the rear track would have required more work and expense. Just because the rear track is a bit narrower, you can still make the car handle just fine when you tune it. Also note that they were putting a lot more weight in the front wheels, so to keep it from plowing like a pig they wanted to get as much front track as they could. Once you settle on the basic setup and spring rates you tune the suspension with the sway bars. If you add more track with a larger rear wheel offset in the back you're going to need to add more rear bar to keep exactly the same balance. 99% of drivers wouldn't notice the difference as all you would have is a bit more understeer when you approach the limit, but if you're racing or running track events it's likely that you'd make an adjustment to get the balance back after such a change.

 

[Minivansomeren]

It's more likely that the rear track was a leftover from the 2000CS and the front end parts came from the E3. Since they were redesigning everything from the firewall forward when they redid the car that's likely what happened. To widen the rear track would have required more work and expense. Just because the rear track is a bit narrower, you can still make the car handle just fine when you tune it. Also note that they were putting a lot more weight in the front wheels, so to keep it from plowing like a pig they wanted to get as much front track as they could. Once you settle on the basic setup and spring rates you tune the suspension with the sway bars. If you add more track with a larger rear wheel offset in the back you're going to need to add more rear bar to keep exactly the same balance. 99% of drivers wouldn't notice the difference as all you would have is a bit more understeer when you approach the limit, but if you're racing or running track events it's likely that you'd make an adjustment to get the balance back after such a change.

Totally agree that 99% won’t notice the change in handling balance. That’s why I’m puzzled by how popular staggered wheel setup. You also wouldn’t notice it visually unless you are on your hands and knees looking from the rear

 

[ElGrecko]

Also, back in those days there was no such thing as staggered wheel setups. Even into the mid 80's standard practice was to keep front and rear wheels the same size, width and offset so that they could be rotated. Porsche was one of the first to go away from that because of the miserable weight distribution of the 911 demanded it. Virtually all other cars were running a "square" setup. Corvettes didn't go away from a square setup until the C4 ZR1 which was a special limited production case and finally in 1999 with the C5. There's a lot to be said for square setups and for daily drivers that put a good bit of mileage they are a good thing. That's particularly true because tires these days last a long time and if you can't rotate them you can end up with needing tires at one end or the other and when you replace 2 sometimes it's hard to get the same tires and other issues with mismatched tires front to rear.

 

['69 2800cs]

I built some 14x8 Weds bavarias where all the width was added to the outside:

Thread 'Custom widened Weds!'

Nov 7, 2016

I recently sent my 14x7 Weds out to Wheelflip (wheelflip.com) to get the rears widened to 14x8. They cut the original 2.5 outer off and welded on a new 3.5 outer.

All the width was added to the outside so they were ET11 before the swap, they are now ET0. (if you're doing the math on the outers the centers move the offset a bit.)

Cost was about $250 per wheel. Service and turnaround was good, but they sent them back unassembled so I had a little work to do.

I got the look I wanted...I've never liked the narrower track in the rear and this fills out the wells nicely. Tires are 195/70/14...

• '69 2800cs
• Replies: 44
• Forum: E9 Discussion

• 

On the rear arches lots of people say they have theirs rolled, but there are two layers of thick steel there. Grind, yes, rolled, no.

 

[Minivansomeren]

I built some 14x8 Weds bavarias where all the width was added to the outside:

Thread 'Custom widened Weds!'

Nov 7, 2016

I recently sent my 14x7 Weds out to Wheelflip (wheelflip.com) to get the rears widened to 14x8. They cut the original 2.5 outer off and welded on a new 3.5 outer.

All the width was added to the outside so they were ET11 before the swap, they are now ET0. (if you're doing the math on the outers the centers move the offset a bit.)

Cost was about $250 per wheel. Service and turnaround was good, but they sent them back unassembled so I had a little work to do.

I got the look I wanted...I've never liked the narrower track in the rear and this fills out the wells nicely. Tires are 195/70/14...

• '69 2800cs
• Replies: 44
• Forum: E9 Discussion

• 

On the rear arches lots of people say they have theirs rolled, but there are two layers of thick steel there. Grind, yes, rolled, no.

Really good to know!

Edit: read through the thread, this is perfect info and I love the look. Did you put a 195 section tire on a 8” wide rear wheel though?

 

[rsporsche]

i know that @vince runs 17" wheels and he uses staggered with 9" rears. look at the FAQ tires + wheels, the link is in my signature below. whether he has rolled the rear lips or not is not in my knowledge. keep in mind that the issue is probably greater about hitting the springs / shocks on the rear than the rear lip. on the fronts it is both, the wider the wheel / tire, the greater chance of contact. the 14" wheel has a smaller contact patch but is wide half way to the wheel.

according to tire recommendations, a 195/70-14 is not recommended on an 8" wheel. the range is 5" to 7". the 205/70-14 is also recommended for a 5"to 7" wheel. the one size tire that i know fits on an 14"x8" wheel is a 225/60-14 ... and i believe one of the few tires made in that size is the BFGoodrich Radial T/A. i believe @Stan has run that size in the past and i believe he might be able to talk about the size fitting. the tread width is 7.5" and the tire width is 9"

 

[rsporsche]

I’ve done a lot of searching on here and found people running 17x9 et20 wheels in the rear, apparently without rubbing. That wheel would be 16mm further out than stock, but not the full inch. Most other people trying to stuff big wheels in the rear have rolled fenders and lowering springs.

remember a 17" tire has a very low profile and a wide contact patch - but the tire is not much wider than the contact patch -
225/45-17 -- dia. 25", width 8.9" / tread width 7.6", rev / mile = 831 <staggered - rear only>
235/45-17 -- dia. 25.3", width 9.3" / tread width 8.0, rev / mile = 821 <staggered - rear only>
245/40-17 -– dia. 24.7”, width 9.8" / tread width 8.6", rev / mile = 841 <VERIFY width available, staggered - rear only>

i just read in the FAQ that @vince is running 225/45-17 fronts and 245/40-17 rears - all wheel lips are rolled.

 

[Minivansomeren]

i know that @vince runs 17" wheels and he uses staggered with 9" rears. look at the FAQ tires + wheels, the link is in my signature below. whether he has rolled the rear lips or not is not in my knowledge. keep in mind that the issue is probably greater about hitting the springs / shocks on the rear than the rear lip. on the fronts it is both, the wider the wheel / tire, the greater chance of contact. the 14" wheel has a smaller contact patch but is wide half way to the wheel.

according to tire recommendations, a 195/70-14 is not recommended on an 8" wheel. the range is 5" to 7". the 205/70-14 is also recommended for a 5"to 7" wheel. the one size tire that i know fits on an 14"x8" wheel is a 225/60-14 ... and i believe one of the few tires made in that size is the BFGoodrich Radial T/A. i believe @Stan has run that size in the past and i believe he might be able to talk about the size fitting. the tread width is 7.5" and the tire width is 9"

Yes, I read the whole faq, I think that is where I saw the info about Vince running the 17x9 et20 wheels that I mentioned. That was good info but not exactly what I’m planning to do.

Luckily 69 2800 chimed in because he essentially did exactly what I want to do! Take a 7” wide et11 wheel and make it an 8” with a zero or even negative offset. In his case they re-welded the Weds.

In my case I want to take my BBS RS005 (11 offset with 1.5” lips and 5” barrels) and rebuild them with 2.5” lips. So hitting springs and shocks will not be an issue because the mounting face (center) and inner barrel will be the exact same. The only thing changing is adding 1” of dish to the outside. But it sounds like ‘69 2800 doesn’t have any rubbing issues, and they look great. I thought he said in his thread that he put 195 section tires all around? which (like you said) is not recommended. Hence why I asked for clarification…

 

[rsporsche]

the question is what is your goal in moving the rear wheel outboard? the standard 16" rear wheel is 225/50-16 and it is 9.2" wide with a contact patch that is 7.5" wide and the recommended wheel size is 6" to 8". i am really curious why you want to push a wheel / tire closer to the lip and not roll the lip. my humble opinion is that you are asking for trouble and are going to run a significant risk of cutting a tire / perhaps bending the fender lip when the suspension is flexing. the other option is to just put a 6" barrel and leave the matching 1.5" lip. there hasn't been any issues on rears with 8" width - 225/50-16 tires on fender lips / suspension ... changing to 9" width with 16" wheels is probably going to hit the suspension and get very close to the lips.

 

[Minivansomeren]

the question is what is your goal in moving the rear wheel outboard? the standard 16" rear wheel is 225/50-16 and it is 9.2" wide with a contact patch that is 7.5" wide and the recommended wheel size is 6" to 8". i am really curious why you want to push a wheel / tire closer to the lip and not roll the lip. my humble opinion is that you are asking for trouble and are going to run a significant risk of cutting a tire / perhaps bending the fender lip when the suspension is flexing. the other option is to just put a 6" barrel and leave the matching 1.5" lip. there hasn't been any issues on rears with 8" width - 225/50-16 tires on fender lips / suspension ... changing to 9" width with 16" wheels is probably going to hit the suspension and get very close to the lips.

I guess I should have been more clear. My goal is 100% aesthetic. I think the car will look better with the rear as wide as the front, and also I like the look of a deeper dished wheel on the back.

Getting a wider tire contact patch in the rear is not a goal at all, although it would be a side-effect if I go this direction. I do enjoy racing and track driving and if anything I prefer a balance tending toward oversteer. Widening the rear would go the opposite direction with balance. But I don’t have any plans to take the E9 on track (too nice, too flexy?) and as we said above, I don’t think I would ever notice the extra rear grip on public roads.

I share your concerns with cutting a tire. That is why I asked how wide people have gone without cutting a tire, or rolling their fenders. I phrased it that way because I know many people (not me) like to stuff wide tires on their car, like the 9” we referenced earlier. I don’t want tires that wide, but I can use their experience to calculate how far out the tire and wheel edge is, and extrapolate to my situation, where I’m only concerned with the outside edge, and not with wheel/tire width. But maybe I confused some people by asking about wheel width, and you thought I wanted wider tires?

Anyway, ‘69 2800’s thread answered my question perfectly and gave me plenty of food for thought - also good pictures of the stance of the car.

 

[rsporsche]

i get it, but if you are going to put a 205/55-16 on an 8" wide wheel ... it don't think its gonna fit that good. the recommended wheel width range for a 205/55-16 is 5.5" to 7.5". the overall width of the tire is 8.4" and the tread width / contact patch is 6.5" ... but moving the outside of the tire 1" is a bit crazy IMHO ... i like the look too, but ... i have said my piece, and i will wish you better luck than i expect you are going to have.

 

[Minivansomeren]

i get it, but if you are going to put a 205/55-16 on an 8" wide wheel ... it don't think its gonna fit that good. the recommended wheel width range for a 205/55-16 is 5.5" to 7.5". the overall width of the tire is 8.4" and the tread width / contact patch is 6.5" ... but moving the outside of the tire 1" is a bit crazy IMHO ... i like the look too, but ... i have said my piece, and i will wish you better luck than i expect you are going to have.

I still think something is lost in translation… I don’t think I ever said I’d put a 205 tire on a 8” wheel. If I do this build I’ll get 225 section tires for the rear. That’s the “side effect“ I mentioned above.

And you say this is a bit crazy, and you don’t think it will work, but I would point you to the thread linked above where ‘69 2800 did the same thing. He had a wheel builder add an extra inch to the outside lip of his Wed‘s wheels, going from 2.5 to 3.5 inch lips. And it sounds like he had no rubbing issues? If anything, his build is more crazy because he later found out that the wheels were originally closer to five offset, meaning it was -7 or 8 in the final product, and therefore would poke out another 5 or 6 mm beyond what I would do. The only other crazy thing about his build is I think he said he put a 195 section tire on the 8” wheel, which I asked about, but he hasn’t responded.

 

['69 2800cs]

I had some slight rubbing on the driver side so I ground the lip down a very small amount.

I used 195’s because it’s what I had. For what I spent I’m really happy with the results.

 

[Drew Gregg]

I have 16X7" BBS Mahle ET11 wheels on my coupe. The previous owner I'm pretty sure put Carl Nelson lowered springs all around, big Suspension Techniques anti- sway bars and Bilsteins. The front fender lips needed to be rounded and the rear lips are original. The Michelin 205/55 ZR 16 tires have just been replaced with Continentals after 20K miles.
The tire shop found 2 of the 4 BBS wheels needed to be trued due to slight dents that I never felt while driving. Low-profile tires and a very stiff suspension probably caused the wheel dents.
I'm just adding this to the conversation for help in deciding wheel/tire sizes, offsets and suspension setup. My car has almost no lean when going around fast corners. But I have no other coupe to compare the suspension at speed.
Pics for comparison.

 

[rsporsche]

I still think something is lost in translation… I don’t think I ever said I’d put a 205 tire on a 8” wheel. If I do this build I’ll get 225 section tires for the rear. That’s the “side effect“ I mentioned above.

And you say this is a bit crazy, and you don’t think it will work, but I would point you to the thread linked above where ‘69 2800 did the same thing. He had a wheel builder add an extra inch to the outside lip of his Wed‘s wheels, going from 2.5 to 3.5 inch lips. And it sounds like he had no rubbing issues? If anything, his build is more crazy because he later found out that the wheels were originally closer to five offset, meaning it was -7 or 8 in the final product, and therefore would poke out another 5 or 6 mm beyond what I would do. The only other crazy thing about his build is I think he said he put a 195 section tire on the 8” wheel, which I asked about, but he hasn’t responded.

a 225/50-16 is a lot wider than a 195/70-14, and the 16 is quite a bit squarer than the 195/70-14, which will have a higher probability to rub on the fender lip. i have said my bit and given you my warning - that's all i have to say.

 

[teahead]

10s

Thread 'Possible Wheel Options - 17x8/9 Staggered'

Apr 11, 2016

Just wanting to know what possible wheel options exist for a 17x8 front and a 17x9 rear with ET20.

For example, love this look but not sure where to find BBS RS wheels or alternatively - and preferred - a BBS replica set. I would like something like this that is an older throw-back design for my build, but not anything like Alpinas.

• jsutton
• Replies: 47
• Forum: E9 Discussion

 

[Minivansomeren]

10s

Thread 'Possible Wheel Options - 17x8/9 Staggered'

Apr 11, 2016

Just wanting to know what possible wheel options exist for a 17x8 front and a 17x9 rear with ET20.

For example, love this look but not sure where to find BBS RS wheels or alternatively - and preferred - a BBS replica set. I would like something like this that is an older throw-back design for my build, but not anything like Alpinas.

• jsutton
• Replies: 47
• Forum: E9 Discussion

Wow. Yup. Another great wheel thread I overlooked. There are just so many!

Pretty amazing that Barry is able to get away with 10s. That is 2” wider than what I’m considering. 1” on the outside, 1” on the inside… I guess part of the secret to his success is stretching the narrow tires onto wide wheels? Like @rsporsche says, it’s not recommended but does help the tires clear the fenders

 

[Maniak91]

19x13" with a offset of -60 and a 325/30/19 tire.
Does this count?

 

[BimRLuvR]

Interesting thread for sure. My car has 16 X 9 BBS RS with 245/45/16 Michelins on the rear. It has rolled fenders. They fit well, and I could (and will) lower the car a bit more. The only downside is that I am having trouble finding a good UHP summer tire in this size.