Wheel diameter question for upgrading E39

[a13antichrist 0]

So, I'm getting some new wheels for my E39 which currently has 225/55R16 tyres; that gives me a total diameter of 654mm.. the recommendation is not to go over 2.5% of the exisitng diameter but I'm thinking, surely that should apply to the FACTORY diameter, rather than the exissting one?

So in fact, if I want to change, I should ignore my current setup altogether & just go with something that's within 2.5% of the original factory setup, in order to keep the speedo/odo consistent, no?

Question then is, are all E39s calibrated the same way at the factory, or are they independantly adjusted depending on whatever wheel/tyre combo is specified for them when originally purchased?

=> I.e., I've read that E39s should by default have a 640mm diameter, is this always the case?

[kiwi535 538]

as long as the original diameter is adhered to the speedo is correct.You will probably find that all factory tyre wheel combos for the E39 result in the same o/a diameter so the 17 in tyre will be a 235 45 17 or a 255 40 x18 ie the profile drops to keep the dia the same.These arent real figures just dreamed up ones!

[a13antichrist 0]

as long as the original diameter is adhered to the speedo is correct.You will probably find that all factory tyre wheel combos for the E39 result in the same o/a diameter so the 17 in tyre will be a 235 45 17 or a 255 40 x18 ie the profile drops to keep the dia the same.These arent real figures just dreamed up ones!

Yeah it's the original diameter that I'm trying to figure out - the current tyres give 654 so I'm trying to find out whether that is in fact the exact original height or whether it was something else.

[martyyn 2]

There should be a sticker inside the drivers door that tells you all the factory sizings for the car.

[zenetti 0]

I am pretty sure the 225/55/16's are factory standard OE fitment, so a 235 or 245/40/18 wil be the correct upsize that you want, or staggered fitment 265/or 275/35/18 at the rear. hope that helps

[hotwire 352]

225/60 15" are standard fit (mine had), 528i had 16" I fitted 235/40 18"s to mine which were from memory only 5mm different in overall rolling diameter to the 15" originals

[a13antichrist 0]

225/60 15" are standard fit (mine had), 528i had 16" I fitted 235/40 18"s to mine which were from memory only 5mm different in overall rolling diameter to the 15" originals

Awesome, cheers guys.. I'm going with 245/40-f // 275/35-r.. should be sweeeeet

[zenetti 0]

I would only go for the 245 275 combo if you have a 540i, otherwise 235 265 will be sweet for a 528i

[martyyn 2]

I agree with these guys, the 275's on the rear will be too much for a 528 IMO.

Do the business nicely on my 740 though

[a13antichrist 0]

I would only go for the 245 275 combo if you have a 540i, otherwise 235 265 will be sweet for a 528i

265/35 makes the diameter 643mm, as ooposed to 649 for the 275/35 - i.e., much closer to the factory diameter of 654.

Though actually I'm now leaning more towards a set of 18x8.5 all around on 245/40; the 245/275 was for a set of Alpina Dynamic replicas but it's more than I need to spend, heheh.

[zenetti 0]

6mm total overall diameter is not going to make much (if any) difference, it is only 3mm top and bottom which you can lose due to tyre wear. 3 pedals comment about 235/45/17 and 255/40/17 equates to 235/40 and 265/35 rears in 18's. All the E39's we have done have been on this combination on a 8' front 9" rear wheel, and we have had NO problems. Remember bigger is not always better

Edited June 15, 2007 by zenetti