What is the lagest size tire I can use on a E34?

[IzzE46]

I have a set of 18x8.5 wheels and need to know what is the largest size tires I can use on the front and back? Can I use 245/45/18 in the front? Or will they rub? Can I use that size tire on 18x8.5 wheels?

[Kudo540]

I know people that have put 275 in the rear and 255's up front.

[IzzE46]

Is this on E34's? Are you sure? I have a 1995 525i. Will 245's work up front?

[shragon]

what's the offset?

i have 18x8.5's as well and my offset is 13mm. i run 245/40-18's all around.

[IzzE46]

I belive it is the same 13mm offset. With your 245 all around, will that rub? How can some poeple run 245 and others 225 on 8.5 wheels? So I am cool with 245/45/18's? Will the tires being 45 instead of 40 make a diffrence?

[shragon]

45 series tires will be too tall. you definitely want a 40 series tire.

what brand rims are they? i might be able to figure out the offset. by knowing the actual offset, we can probably give you better advice.

my 245's rubbed a little up front, and i had to get the fenders rolled. 235's had no problems.

some people are able to run wider tires in the back due to the offset. 13mm offset really pushes the tires out, almost flush to the fender, which leaves little room for a wider tire.

[IzzE46]

They are RH wheels Alutec style 18x8.5

[phatfarm]

It also depends on if your car is lowered, and if so, how low you have it.

[Cacatfish]

Ive seen 255/40-17 all around on m5 throwing stars and lowered m5 (pretty low) with no rubbing. I had 265/35-18 rear and 235/0-18 front without rubbing.

[Matt H]

I was using 235/4018 and 265/35/18 on Hamman HM2's with no problems. The rear tire was a little wider than I wanted on an 8.5 in wheel though. I just swapped to 235/40/18 all around when I changed the tires about 3 weeks ago.

[IzzE46]

Thanks for the help guys! Do you think I should run 235/40/18 all around or go with 225/40/18 all around?

[shragon]

the minimum you should go is 235/40-18 all around.

[Rob Levinson]

Anything wider than a 245 in the front of a 5-series (any 5-series, the front suspension is basically the same on E12, E28, E34, E39) will cause tramlining or wandering. This means something like a 245/40-17 (.6" smaller diameter than OE spec for sharper steering response) or 245/40-18 (.4" larger) is acceptable. With this width, you can use a wheel between 7.5" and 8.5".

18" front:

http://www.robertlevinson.com/M5_Touring/images/E39M5wheels/IMG_2201.jpg

Front offset should be about 20mm. While you can run more offset, anything much more than that will start to affect the steering response. If you're buying new wheels, resist the urge to get the "Euro look" offsets at lower numbers. Why buy into fender rubbing and tramlining?

Normally, rear offset is also about 20mm. With the correct offset around 22mm, you can fit a 275. This means 275/40-17 (only 3.7% different than the front 17" size above, within the 6% ABS threshold) or 275/35-18 (a near-perfect match for the 18" size above). With this width, you can use a wheel between 9" and 10".

17" rear:
http://www.robertlevinson.com/M5_Touring/visuals/M5_rear_wheel.jpg

http://www.robertlevinson.com/M5_Touring/wa/images2/tires_low_long2.jpg


Note that neither of the above sizes/offsets will require fender rolling.

If you want to run the same size all around, I recommend the 245 width. The E34 is too big a car to suffer with anything smaller if you ever drive in "sporty" manner.

[tonyluvsilvia]

Rob,
Looking at your site gave me some ideas also... would the V-12 directly swap into the E39 540 since it's very similar to the E38? I guess other than being exotic, the power increase wouldn't be as tremendous as a SC kit. I haven't researched the costs involved in the swap, but I would wager that it would be much more costlier than a SC- perhaps that's why I haven't seen V12 E39's?

[Rob Levinson]

It would fit. It's been done, and would make a hell of a fun ride!

If you do it with the 5.4l M73 V12 from the E38, the torque prodigious, just above or below the E39 M5 depending on what point in the curve... and with 90% of max torqe at under 2K rpm, you can roll on the throttle in just about any gear at any speed and just go. This is more torque than most SC kits with understressed factory-part reliability. My 750iL/6 will lay two lines of black rubber for at least 15-20ft without a problem. It's a little hard on the driveshaft (http://www.robertlevinson.com/seven/ds/), but then you learn to build stronger than OE-spec.

Cost might be more, but the end result would justify it.

If you do it with the 5.0l M70 V12, it would be a lot cheaper as the E32 750iL cars do not hold any value. You can pick up a mechanically decent 750iL for just a bit more than the cost of a SC kit, and sell off the rest of the chassis. The upside is the M70 can be easily fitted with the 6-speed manual from the 850i/850CSi. The downside is the M70 is nowhere near as reliable as the M73, and down on power in comparison. Still would be a lot of fun.

- Rob

[tonyluvsilvia]

Where have you seen the M73 in an E39? It would be fantastic if you can show me some pics or websites. My car is for sale at the moment, but I wouldn't rule out the possibility of a project V-12 E39 later down the line with a high mileage, early E39.....

Thanks

[Rob Levinson]

Originally posted by tonyluvsilvia
Where have you seen the M73 in an E39?

http://www.supercars.net/garages/Murtaza/38v2.html

- Rob

[IzzE46]

Ok, can I use 245/45/18 all around? Please let me know I need to buy tires soon. Thanks

[shragon]

too tall. use 245/40-18.

[IzzE46]

Ok thanks!

[Dark Helmet]

hey rob, you hit on some interesting points that we managed to discuss while spending 44 of 60 hours in a car over the weekend... that is.... V12 swaps.

namely, and seriously, how do you get an M70 into an E28??? :D:D:D:D:D

and is it cheaper with the M70 to replace the engine management system with a stand-alone batch-fire type, or try to live with throttle-position-sensor hell???

[IzzE46]

Can I use 225/40/18 in front and run 255/40/18 in the back? I wat to run a stagered set up?

[Dark Helmet]

absolutely, that will work fine... you might even run 225/45s in the front.

[Rob Levinson]

Originally posted by dasMafia
hey rob, you hit on some interesting points that we managed to discuss while spending 44 of 60 hours in a car over the weekend... that is.... V12 swaps.

namely, and seriously, how do you get an M70 into an E28??? :D:D:D:D:D

Bring money. Lots of it. Anything can be done.

My serious suggestion to you is not to waste either a good E28 chassis or a good M70. It's not a good marriage.

Why do I say that? A few reasons:

1) The E28 is tire-size limited to 255s in the back (short of having custom bodywork) which the M70 would abuse mercilessly when asked to move a chassis weighing roughly 1,000lbs less than it was designed for.

2) The E28's engine bay is simply not conducive to a motor that physically large. You could make it fit, but the effort would be beyond reasonable.

3) The E28 is already a little tail-heavy. Add that much weight in the front and so much power coming out of the rear with a rear suspension already prone to twitchiness, the net result would be like driving a lawn dart.

A much better idea is to install it in an E34. The E34 engine bay accomodates the M60 V8, a motor found in the E32 740. The M70 fits in rather well, and has been done. The chassis dynamics and stiffness of the E34, coupled with the ability to accept larger tires, makes it a prime candidate to become a 550i.

One last consideration is cost: any E28 clean enough to put all of this effort into will cost almost as much as a decent E34. Small portion of the total project budget.


Originally posted by dasMafia
and is it cheaper with the M70 to replace the engine management system with a stand-alone batch-fire type, or try to live with throttle-position-sensor hell???

M70s work fine with OE engine management. You will get better results (after a lot of tweaking and custom work) with something like a TEC3, but that would cost as much or more than the engine itself.

[Dark Helmet]

thanks man... I have the solid E28 chasis sitting in the parking lot... the requisite M30 residing within its bowels at the current moment strikes me as a piece of machinery not long for this world... can you say head gasket??? :D:D:D

[Dark Helmet]

but, in any case, are there any particular E34s that would be preferable for this conversion??? I don't know enough about them to really do much of anything at this point... all I know is that their M30s are better than mine...


oh, and the second half of your #1... that was the whole point in the first place! :D:D:D

[Dark Helmet]

and... (sorry, its friday and I'm bored) would an M52/S52 be easy to fit into the E28 if the M70 is not??? (not interested in the V8s, too much money, not enough fun)

[Dark Helmet]

.... and I assume anything I can fit an M70 into I can fit an M73 into as well???

[/post whore]