What size tyres for my ac's?

[rowanhol 0]

hey guys just got some ac's off trademe but the tyres they came with are rooted and too big for my car . the wheels are 8 1/2" wide 17's, have 8 1/2J x17 h2 e13 printed on em. came with 235 50's but they rub on the spring cups up front and the large profile looks ridiculous on the car.

was thinking 225's all around with 40 profile at the front and 45 at the back.. what do you think?

heres how odd they look on the car at the mo..

[Yuen 16]

I'm not sure if the E34 is different, but for E36, you'd run 17x8.5" wheels with at least 225/45/17, and it can go up to 245, even 255 no problem in terms of width. But the profile... gotta check with a tyre calculator, can't remember the exact sizes.

[zenetti 0]

I think you should be running 235/45/17's all the way round from memory or could go 225/45 and 255/40 if you wanted to.

[cainchapman 0]

zenetti has it right. 235/45/17 on 8" all round. Although they had a stagger on the rear 255/40/17 on 9".

[rowanhol 0]

Cains on the money 235- 45 17 - Offset looks wrong in photo.

the offset does look wrong in photo but seems fine in person..

just not too sure if 45 profile is going to be low enough up front to stop it rubbing,how much difference in mm is there between a 50 and 45 profile tyre? with half worn 50 profile tyres they wore a groove in the tyre about 3mm deep

does anyone know what the correct offset should be?

[bezzal 1]

I have E31 840 wheels on my E34. They are 16x7.5 ET13. I have no problem with rubbing etc. Even at full lock.

The wheels I run are 245/45R16 They are quite a bit shorter than the stock wheels it came with. I'm doing just under 2500rpm at 100kph, manual trans.

So that should give you a base to work off with your 17's of the same ET.

Edited April 25, 2007 by bezzal

[kiwi535 538]

std e34 offset is et 20,and 235 45 17 is correct for diameter.235 may be a tad small for 8 and a 1/2,so 255 40 may be better,235s look smaller in profile on my 8 and 1/2 compred to the 8 in rim,presumably beacause they are slightly stretched.My ET15 17x8 1/2 definetly sit out more than ET20 17 x8,s.So i run 235 45 at the mo with std mtech suspension no rubbing at all,your car definetly looks lower tho

[rowanhol 0]

They do sit out a liitle further than the standard wheels as you would expect being et13 rather than 20 or 22 but just read up and apparently they are fine. and it's not that thay are rubbing on the guards(well not much) its more that the fronts are rubbing on the spring cup.

thinking 235/45's are going to be the choice.

[rowanhol 0]

oh and yeah the car has been lowered by previos owner.. thinking of going an inch lower again in the front to even it up.. you know how the front always sits up on e34's. so myte have to take that into consideration with tyre choice

[Mike 1]

std e34 offset is et 20,and 235 45 17 is correct for diameter.235 may be a tad small for 8 and a 1/2,so 255 40 may be better,235s look smaller in profile on my 8 and 1/2 compred to the 8 in rim,presumably beacause they are slightly stretched.My ET15 17x8 1/2 definetly sit out more than ET20 17 x8,s.So i run 235 45 at the mo with std mtech suspension no rubbing at all,your car definetly looks lower tho

you can't really say what the standard offset is for a car, as the ideal offset changes depending on rim width. (unless of course they came with 17x8 from factory with that offset). The wider rims you get the more critical it is to get the right offset.

[zenetti 0]

235/45/17's will be fine, the overall diameter is 25mm ( as 3 pedals said 12mm lower, but x2 as you have top and bottom) less than a 235/50, circumference is about 75mm less. You shouldn't have any isues even if the car has been lowered. You are probably best to go with 235/45 rather than 255/40's as this will give you more clearance esp if you are going to 'sack' the car

[kiwi535 538]

The M5 came std with 17 inch wheels originally but later e 34 models(like cains) had either a 17x8 with 20 mm offset or 17x9 on the rear(not sure what the offset was on those wheels,but the rears are not so critical as the fronts re offset.This is leaving out the 18 in wheels on the 3.8 M5 as this wil cloud the issue even further

[bezzal 1]

Offset is rim width dependant as mentioned by "mike" - the offset will change to ensure the tyre sits optimally between the suspension and the guard. If the offset stayed the same for a 9 inch rim as an 8, then ALL the extra width would be on the outside, so the offset should decrease as the rim width increases. Until of course there is no clearance on the inside.

I thought the offset was from the center regardless of width size. So I would have thought if you go from a 8 inch to a 9 inch you would end up with a half inch extra on each side of the offset???

[kiwi535 538]

not necessarilly.the offset is the distance from the centre line to the mounting surface of the wheel.Putting a half in on either side of the whhel is probably what happens but you may not be able to move the inside surface in by 13 mm so you have to have a 13 mm offset to shift the wheel back out by 7mm.(20 - 13 = 7)

[zenetti 0]

I agree with 3pedals if it is rubbing on the bootom of the spring plate a 235/45/17 will be sweet

offset is measured from the centre of the wheel to where the wheel bolts to the hub, is also know as backspacing. The higher the offset the further in the wheel will sit all things being equal.

www.wheelsmaster.com/rt_specs.jsp

go to the above link for a easy explanation, it even lets you play around with different widths, tyre sizes etc.

[rowanhol 0]

thanks guys for all your help, just pricing up 235/45/17's.. hmm might hold off for a while, wallet feeling the pain..

[rowanhol 0]

finally got some 235/45's for the schnitzers, looks sooooo much better, and doesn't rub(always a bonus)

cheers for the help guys