TX530i I am not sure who you were asking about their wheels. What are you trying to accomplish with the tires? Big as you can get on the rears without rubbing or just reasonable tires that fit?
The tire rack size recommendations are not wrong, but you have more options.
Here is some info that may somewhat helpful. Keep in mind your wheels sizes are slightly different dimensions than these combos, but your offsets are different too which may cancel out any width differences. I am not great at doing those offset calculations so I can't say for sure. Anyway here are some OEM setups
2003 540i Sport came with style 37 wheels
- 18x8 et 20 Front with 235/40/18
- 18x9 et 24 Rear with 265/35/18
M5 came with style 65 wheels
- 18x8 et 20 Front with 245/40/18
- 18x9.5 et 22 Rear with 275/35/18
Also a lot of people put style 37 wheels from an e38 on their e39s as the e38 style 37 wheels are more plentiful. The e38 wheels are
- 18x8 et 13 Front (not sure what size fronts people run with these)
- 18x9.5 et 25 Rear (275/35/18 or 265/35/18 are both popular sizes)
Actual Tire Size Variation
fyi if you are unaware, the tire rack is a good resource because they list actual measurements for almost every single tire they sell. Actual tire width can vary greatly from tire to tire and from manufacturer to manufacturer. Look at the
tread width and
section width numbers when you are comparing tires.
Alternate Sizes
As you probably know you can run slightly different sizes than the ones listed above depending on what you are trying to accomplish. You just need to make sure you stay within the min/max wheel width for the tire size. And use a tire size calculator to make sure you are staying with a 3% difference from new size to old.
1010 tires calculator lets you compare up to four size to your original size.
If it is of any help I recently upgraded my 530i sport from 17" to 18" wheels (OEM style 37) and I considered the following
Rear tire sizes
- 245/40/18
- 255/35/18
- 255/40/18 (Tire size calculator said this was just barely under the acceptable limit)
- 265/35/18
As far as larger tires go, some people run 285s in the rear and report no to minimal rubbing, but I think those people all at least had rolled fenders. Keep in mind the M5 had rolled fenders from the factory and the rear M5 wheel liners are shaped differently to accommodate the larger tires without rubbing.
So if you are going to run 275 or larger you will probably need to roll your fenders. And depending on your suspension and/or whether you carry people in the back of your car you may get slight rubbing from the wheel liners depending on the specific tire.
Square
Also did you already receive and open the wheels? Unless you want the staggered look I would think about buying a set of four identical wheels so you can have four identical tires (square setup) rotate your tires. Finding a set of 9" wide wheels would probably be ideal. But if you really like the wheels you have you could buy four fronts or four rears of the replica 29 wheels.
Although if you buy four front replica 29s you would be limited to 255 max as they are 8.5" wheels and a 265 is going to need at least a 9" wheel.
And if you have four 9.5" rims you may have to run a spacer to clear the strut upfront depending on the offset and tire sizes. For example I know a bunch of the M5 guys run square 275s need 3mm-5mm spacers up front. I don't know if the hub to strut distances are the same for the non M cars, so you might have more or less space than the M5 guys. Also the replica 29s offset is slightly different so that may may help you(but my offset math could be wrong).
Rotation
Some of the tires might not be directional, but double check that those non directional tires do not have a specific inside and outside edge tire tread pattern. Unless I am confusing myself, if they have a specific inside and outside edge then rotating them side to side is not going to do any good. As the inside edge is still going to be on the inside and therefore the negative camber is still going to wear the inside edge of the rears faster than the outside edge.