Sarge

255/40/19 is slightly wider and taller than the stock fitments for this car, but 255/40/19 is an optional fitment on the M5.

I'm contemplating using a set of new tires I had bought for another car on 19" replica M5 wheels with ET40. My concern is (1) will they rub anything, and (2) will they still fit inside the wheel wells (I don't want them sticking out past the tops of the fender lips, as we have lots of rock in Wyoming).

Anyone used this size on a 535xi wagon?

Thanks in advance for any input.

mmitev

According to my research, fitting 255 tyres at the front of a non-M E60/61 has generally not worked. The M5 is a different story due to wider front fenders.

That said, I've only read about this on a non-x E60 using OEM M5 166 wheels, and the problem seems to be mostly the low offset of the OEM wheel causing rubbing on the outer side of the fender.

If you are lucky, your combination of xi stock offset and replica wheel offset might alow you to fit the tires.

A simple calculation comparing:
- the stock and replica ETs (43-40=3 mm outward push) and
- the stock and replica wheel width (8 vs 8.5 inch resulting in 0.25 inch or 6.25 mm outward push)
shows an overall outward push of the wheel of 9.25 mm (=3+6.25 mm), or equivalent to a 9.25 mm spacer.
On the tyre level, the virtual spacer is 3 mm + 5 mm (=(255-245)/2), or together 8 mm.

On a normal E60, a spacer of 10 mm upfront is not a problem. Fitting stock M5 wheels results on a normal E60 results in a virtual spacer of 14 mm, which is a problem due to these additional 4 mm.

IF your xi front stock wheels are similarly positioned as stock E60 wheels, the 10 mm should not be a problem too.

Long story short: you have to try them on, and worst case put 245 tires on the wheels..

Lotus99

I used the calculator at the top of this forum page, which also confirms a 9 mm outward push, but I'm not sure how you come up with 14 mm? The calculator also points out less clearance on the inside of the wheel too, I'm guessing from the wider wheel.

The calculator says: "3mm LESS clearance on the strut side, and the outside edge of the wheel will EXTEND an extra 9mm".

What do you mean by the "tire level" also and are you trying to say that 8 mm is outward push too?

mmitev

14 mm is for OEM M5 166 wheels on a non-x E60.

I mean that on the same wheel, 8.5 in our case, you can have a 225, 245 or 255 mm tyre, all with different width. The 225 tyre is most likely to fit in the fender, as it is narrowest. This is why I distinguish between wheel width and tyre width.

The 8 mm is a outward push as well. Its 3 mm from the offset plus 5 mm (half of the 10 mm difference between the two tires width). Using the same logic, the inside of the tyre moves 5-3=2 mm towards the strut.

Lotus99

Good point on considering tire widths too. I'd not thought of that before. I think the calculator only does wheel changes. So the wheel will stick out 9 mm more than before, and the tire 8 mm. How can one figure out the outermost point then, which is sort of all that matters anyway?

For example, in an unusual situation where your new wheel's width and offset are the same as the old one, but you run fatter tires, it's how far the new tire will push out you care about as far as rubbing goes.

The other thing to consider is making sure that the speedo isn't too far off, since the diameter is now different from before (which in this case, I forgot to mention that it's 5% fast).

Sarge

That calculator is quite helpful. Looking at it, I'm thinking the 255 may be too much in front. All things considered, I think I will go with a 245/40/18 instead (stock diameter) on a wheel with an offset in the ET30 to ET40 range.


As for my question above (255/45/19, ET40, 19x8.5/9.5 f/r), the calculator says this:

FRONT:
10mm LESS clearance on the strut side, and the outside edge of the wheel will EXTEND an extra 16m

REAR:
22mm LESS clearance on the strut side, and the outside edge of the wheel will EXTEND an extra 28mm

Lotus99

Not sure what you did there, but for the front, it should be what I typed above, not yours. Double check them.

I got "3mm LESS clearance on the strut side, and the outside edge of the wheel will EXTEND an extra 9mm" for the front, which matches what mmitev came up with as well.

For the rear I get "16mm LESS clearance on the strut side, and the outside edge of the wheel will EXTEND an extra 22mm"

Also, I assume you mistyped when you wrote in this last post 255/45 instead of 255/40.

alexio

SO, I don't want to lower my car as the front bumper scrapes enough as it is on ramps and poor northern california roads, but I'd like to upgrade to 19" wheels. I'm thinking that if I go with a slightly thicker wheel (and greater overall diameter) I could get away with not making the car look "lifted". So, has anyone fit a 19" wheel with a 40 aspect ratio on the front (and I'm assuming a 35 aspect ratio on the rear?) so as to keep the diameter of all four tires the same for our xi cars? any pics?

thanks.

norsecarnut

You aren't speaking in complete thoughts so it makes no sense. a 40 tire on 19" will fit fine up front in terms of the diameter and clearances. Why would you assume a 35 on the rear - unless you plan to use staggered set up? Either way, it's not as simple as saying 40 and 35, it is also very important to match the total diameter, which is going to depend on the tire width as well. You just have to spend the time looking at the tire specs to see what combinations work. M5's and other rwd cars don't require identical sizes but xi should be darn near identical.

norsecarnut

There's a lot of calculator gibberish I just can't take the time to research but it's probably a good overview, except that not all tires have the same end shape and size on a rim. For instance, I have Bridgestones on for summer which I like because they are sort of wide at the sidewall, and provide a nice rim protection by being wider than the rim lip. The continentals that were on the Audi were flush with the rim so I curbed all 4 wheels in the first 6 months like a dork.

The reason the M5 uses that 255/40x19 is because the rim is WIDER than the rims normally found on an E61. Usually an E61 will have an 8", maybe and 8.5" front wheel width and thus a 255 tire is ideally, too wide. Hence the 245 tires on E61's.

The tire height is not the problem. I run a 245/45x18 which is 1" taller than stock E61 245/40x18 and it's great. I have these on 8.5" wide rims with an ET29.

You could use the above wider tire you mentioned, but it should only go on a 9" wide wheel, which is going to be a rare find. The m5 rep is surely not a 9" wide version so that 255 tire is going to get shaped weird and not handle as well, potentially very unsafe actually. If you go away from the ideal match, it should never be wider for the tire. "stretching" the tire onto a wider rim is much safer, up to a point of course, but with a tire too wide, it shifts/deforms, laterally when cornering or during any car weight transfer. Don't do it!

I know of a rim you could do though, it would be one of the m3 sets, the csl I think, 9"/10" with ET 31/25 . You can find it here http://felgenkatalog.auto-treff.com/ and buy them from this bmw dealer who discounts for bmwna club members http://www.trademotion.com/partlocat...72&catalogid=0

Or, just look through for other 9" wide rims with an ET no more than 31, which might be pushing it. You may have to go aftermarket to get a 9" that fits into the front.