[e92atr]

Hi Guys,

New to the forum, however owned my 330D LCI e92 for coming up 2 years now.

Fear not i have used the but with no success!

My question is basically is there a specific reason BMW run 35 on front and 30 on the back and what would be the consequences if I ran 35 profile all round?

Reason for the question is the Eagle F1s im looking at putting on are £50 cheaper in the 35 profile than they are in the 30!!

Currently running 225/35/19 front and 255/30/19 back. Looking to run 225/35/19 front and 255/35/19 back, hence the question.

Any help would be appreciated.

Cheers
Alex

[Chappers 71]

I suspect it'd adversely affect the handling/balance of the car but I don't actually know.
If you do fit them & it affects the ride then you haven't saved anything, it'll just end up costing you more. Personally I wouldn't do it.

Up until my last rear tyre change I ran the F1's & they were always between £140/£155 each including fitting & tyre disposal & I've had 7 pairs of rears. How much have you been quoted?

[e92atr]

very similar prices, around 310 320 for the pair!

I do feel like very smart and well paid people at bmw have done this difference in profile for a reason!

[ECSTuning]

The reason is to keep rotating diameter the same (or very close to the same) front to rear while allowing for staggered tire widths.

When you start getting the tire diameters too far apart the computers (safety features) start having issues, and with an AWD car you'll start running into possible transfer case issues.

-James

[bfleming]

The widths are the key here. The rear has wider wheels for traction, so needs a wider tyre on that wheel. The 35 - or 30 - is the height of the tyre expressed as a percentage of the width.
So a 225/35-19 front tyre will be 225mm wide, and the height will be 225mm x 35% = 78.75mm.
The rear 255/30-19 will be 255mm wide, and the height will be 255mm x 30% = 76.5mm - so pretty close to the front. Changing this to a 35% tyre will change the height to 89.25mm - a huge difference over the factory specified ratio. This will upset things like ABS and Traction Control, as the hub rotation speed between the front & rear axles will be way out.
If you want to change to cheaper more comfortable tyres, swap your wheels for 18's. The permissible tyre sizes are on your tyre pressure sticker.

[rasa bmw]

i ahve 225-40-18 allround on my e46..i had mv2 original wheels with same set up,and now after market 9j rear and 8j front..handles absolutely great,never noticed any difference and traction is great.been like this for 2 years out of the 4 ive had it.only thing is,is the wheel is prone to curbing on the rear as it sits proud of the tyre..uniroyal rs3 tyres.

[IanS100]

Originally Posted by rasa bmw

i ahve 225-40-18 allround on my e46..i had mv2 original wheels with same set up,and now after market 9j rear and 8j front..handles absolutely great,never noticed any difference and traction is great.been like this for 2 years out of the 4 ive had it.only thing is,is the wheel is prone to curbing on the rear as it sits proud of the tyre..uniroyal rs3 tyres.

If the change isn't declared and accepted by you're insurance company they 'could' prove difficult in the case of an accident

[E60525d]

Originally Posted by e92atr

Hi Guys,

New to the forum, however owned my 330D LCI e92 for coming up 2 years now.

Fear not i have used the but with no success!

My question is basically is there a specific reason BMW run 35 on front and 30 on the back and what would be the consequences if I ran 35 profile all round?

Reason for the question is the Eagle F1s im looking at putting on are £50 cheaper in the 35 profile than they are in the 30!!

Currently running 225/35/19 front and 255/30/19 back. Looking to run 225/35/19 front and 255/35/19 back, hence the question.

Any help would be appreciated.

Cheers
Alex

That works out to be a 4% difference in circumference between the 2 tyres. I have heard a 3% difference is fine and within tolerance.

I would try to stick within 3%. Search and you will find people have upsized in profile without issue.

http://www.e90post.com/forums/showthread.php?t=132580
http://www.bimmerfest.com/forums/sho...d.php?t=607854
http://www.e90post.com/forums/showthread.php?t=142543
https://www.auto-treff.com/bmw/vb/sh...89#post2263489

[mjn77]

I fitted 225/40/18 all round on my MV3s for the winter.

[Shanusascarabus]

Hmmm my e92 335i has aftermarket alloys on and is sat on 235/35/R19s all round.... is this an issue.... it sure feels ok to be honest.... didn't think tyre sizing was such an issue

[e92atr]

So from what i have read i am just as well staying with the current sizes. I do eventually plan to go down to 18s and have fatter tyres but purely because i like the racing wheel and fat tyre combo!

However for the time being i think ill just stick with the current set up of 35 on front and 30 on the back! Better safe than sorry.

Thanks for all the replies!

[rasa bmw]

Originally Posted by Shanusascarabus

Hmmm my e92 335i has aftermarket alloys on and is sat on 235/35/R19s all round.... is this an issue.... it sure feels ok to be honest.... didn't think tyre sizing was such an issue

probably because they are a square set up, ie not staggered,and them tyres are fine,,its just you get folk who will say you will die/insurance void/the worlds ending etc etc