Tyre change help

[williamdefender]

His folks
I recently fitted some BMW 397 alloys and they look great . They came with run flats which where OK but I would like to ditch them now . Ive had the whole run flat ride issue before with a 320d and found that Goodyear eagles sorted my problem and really improved the driving experience .
So I need some help please .
Here's my current setup
BMW 397 alloys 18x8 et34
Run flats 225 45 18

Can I go to 225 40 18 ?
I don't mind the height dropping as it will improve the stance of the motor and would actually prefer that as I think the car sits a little high and don't want to changing springs at this stage .

If you where to change tyres what size/make to you think would work best .
Thanks all

 

[MACK]

Basically the change to non ruflat tyres is want half the non M owning forum has done. 225/40 is the correct tyre size for a non M on the front anyway although some (including myself) run M tyre sizes which would be 225/45 front and 255/40 rear as the extra profile makes them a bit comfier but are pricier, as a side benefit the speedos are deliberately under reading from the factory, the change to M sizes corrects that.
Rear wise standard is 255/35 (or 255/40 for the M) 225/40 is so near in rolling radius to 255/35 it wont make any difference to the speedo etc so you should be fine all round.

 

[NC-ZC]

See this recent post below;
http://www.z4-forum.com/forum/viewtopic.php?f=2&t=96598
Following the guidance from some very helpful forum users I have been delighted with the results.
Cheers
Neil

 

[williamdefender]

Been doing my homework with pricing .
Kwikfit have a offer on at the minute online £86.50 each online
Thats £346 and if i go through quid then i get 3.5% which is £12.11
Now down to £333.89
Another live offer with kwikfit - buy four goodyears and get a £40 love2shop voucher .
If everything goes to plan than I'm at £293.89 fitted .

Only thing I'm stuck with is the wider rear . Should i go for a 255 rear or indeed will a wider rear fit a 18x8 wheel .
appreciate the help folks

 

[williamdefender]

just went with the 225 40 18 . Looking forward to improving the drive

 

[NC-ZC]

I have been very please with this set up on my 3.0 si Coupe - it's transformed the drive;
Goodyear Eagle F1 Asymmetric 3's
Front - 225/40 R18 Y
Rear - 245/40 R18 Y

 

[Steve84N]

That's what I run on my coupe and it also gives an accurate speedo.

 

[mjennings23]

I have been very please with this set up on my 3.0 si Coupe - it's transformed the drive;
Goodyear Eagle F1 Asymmetric 3's
Front - 225/40 R18 Y
Rear - 245/40 R18 Y

Any particular reasoning for the 245/40 rather than stock 255/35 on the rears?

 

[Steve84N]

Less stagger gives less understeer, more sidewall gives better ride, larger circumference gives more accurate speedo. It's actually the ideal recommended width for an 8.5" wheel where 255 is the maximum so fits the wheel better too.

 

[csquire4]

You could also check the price of Dunlops, they are just a brand name now made by Goodyear, specs seem similar.

I use Dunlops, good price, great wet grip, smooth and quiet - can't comment on longevity but I'm low mileage driver so less of a concern.

 

[williamdefender]

Got the tyres changed and just as expected the tram line problem has disappeared . Smooth drive in the car now however I've hit a major issue . Whilst my concern was about fitting 225 40 18 on the rear that turned out not to be a problem . Its the front where the issue , on hard lock the tyres are rubbing . Cant see a way out of this , maybe spacers or something . Just have to live with it now that the dosh is spent , unless anyone can advise of the use of spacers . I know the 225 45 18 was fine before but i couldn't seem to source that size in a goodyear eagle. Finding the problem when reversing out of driveway or parking space etc

 

[mr wilks]

Got the tyres changed and just as expected the tram line problem has disappeared . Smooth drive in the car now however I've hit a major issue . Whilst my concern was about fitting 225 40 18 on the rear that turned out not to be a problem . Its the front where the issue , on hard lock the tyres are rubbing . Cant see a way out of this , maybe spacers or something . Just have to live with it now that the dosh is spent , unless anyone can advise of the use of spacers . I know the 225 45 18 was fine before but i couldn't seem to source that size in a goodyear eagle. Finding the problem when reversing out of driveway or parking space etc

Spacers will increase your problem so forget those , strange that you have dropped profile from 225 45 to 225 40 yet now you have rubbing ? That could well be the fact your old tyres were well down & the new are on full tread so either wait a few thousand miles or drop to 215 40 fronts ?
If you turn the wheel & look up into arch liner you should see exactly where the tyre is catching as it will have marked through the crud very often its literally a fag paper difference & sounds far worse in cabin than it actually is

 

[williamdefender]

I know what you mean now about spacers so thats shelved . The older tyres had almost 7mm on them , I'm going to investigate some more and as you say just run with it . cheers