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[ichibanumba1]

Besides speedo calibration being off, can anyone tell me what would happen if I increased my overall rolling diameter by 1 inch?

To be clear, I'm not talking about increasing rim size and decreasing tire profile to stay at the same rolling diameter as stock, but rather moving up a tire profile size.

Assuming I keep stock suspension, I wouldn't imagine any problems with clearance...

[edirtaynine]

ur e92 will look like an X3 coupe.

[ichibanumba1]

I doubt that. if anything my rolling diameter would be m3 sized..

[Tom K.]

It will also have the effect of decreasing the overall gear reduction by about 4~5%. In other words, you will turn about 100 fewer revs at 60 mph in top gear - at the expense of slightly slower acceleration.

Tom

[will.c]

Per your description:
- more comfortable
- less road feel & slower steering response
- less torque at wheels = slower acc & less braking power
- more fuel efficient due to relatively lower revs at same speed
- car sits higher & less wheel gap
- last but not certainly least, will rub in the front (I had 225/50/17 winter tires, OD increase of about 0.75"; fronts rubbed inside fender wells)

[Hybrid For Life]

Personally I don't think 1" is all that huge of a difference, but yes all the things listed above are true. For me I would personally go with smaller diameter if anything.

[ichibanumba1]

Originally Posted by Tom K.

It will also have the effect of decreasing the overall gear reduction by about 4~5%. In other words, you will turn about 100 fewer revs at 60 mph in top gear - at the expense of slightly slower acceleration.

Tom

Thanks! Would you know how far off the speedo calibration would be?
Would speedo reading 61-62 mph and actual speed be 60 sound about right?

Originally Posted by wonho

Per your description:
- more comfortable
- less road feel & slower steering response
- less torque at wheels = slower acc & less braking power
- more fuel efficient due to relatively lower revs at same speed
- car sits higher & less wheel gap
- last but not certainly least, will rub in the front (I had 225/50/17 winter tires, OD increase of about 0.75"; fronts rubbed inside fender wells)

Thanks!
Very helpful indeed
Are you lowered at all?
Per tire rack, I'd have an OD increase of 0.6" in the fronts, rears would be OD increase of 1.2. Both of which are less than most people's lowering heights, but stock suspension is also softer meaning more spring travel....

I think the rears scare me a little more

Originally Posted by Hybrid For Life

Personally I don't think 1" is all that huge of a difference, but yes all the things listed above are true. For me I would personally go with smaller diameter if anything.

Thanks! I agree that 1" shouldn't make a big difference, it's not like the Lexus SCs I see rolling around on 24s I would normally feel the same as you for greater acceleration and braking power, but moving up to 19s means a fairly slim rubber and and with no plans of lowering the car, closing the fender gap wouldn't be too bad in my books. I also drive 90% freeway.

[will.c]

Originally Posted by ichibanumba1

Would speedo reading 61-62 mph and actual speed be 60 sound about right?

Thanks!
Very helpful indeed
Are you lowered at all?
Per tire rack, I'd have an OD increase of 0.6" in the fronts, rears would be OD increase of 1.2. Both of which are less than most people's lowering heights, but stock suspension is also softer meaning more spring travel....

I think the rears scare me a little more

No prob!

It's my understanding the speedo reads higher than actual speed by about 5% give or take a few, so if anything you should be closer to actual with your type of OD increase.

I have stock sport suspension. It didn't rub in terms of fender lip. Actually drove fine even with bumps and stuff. The outer edges of the front tires rubbed inside of the fender wells only under turning while reversing. I lived with it fine. Rears I had no prob. I think you'll be fine but don't take my word for it. Sorry for the crappy pics, but take a look. Note 17" rims tho, with above-mentioned tire size all 4 sides, hence the SUV look

[ichibanumba1]

Thanks for the pics!
What offset are your rims?

[Saintor]

I just did the same .... today!

I was fed up to repair 3 bent wheels and to replace 1 blown tire. Never had any issue with my 225/45/17 tires.

So OUT the 225/40/18 and IN 225/45/18. New Bridgestone RE970AS for me.

My car is seriously lowered (garage basically said 'don't come back', 90% of them have issues raising it... thanks I had my racing jack in the trunk).

I had concerns about rubbing. It is a close call *but they don't rub*. It was a gamble.

What I didn't expect is that high tire walls accentuate the effect of lowering, esthetically. Very happy with the initial results.

[ichibanumba1]

Originally Posted by Saintor

I just did the same .... today!

I was fed up to repair 3 bent wheels and to replace 1 blown tire. Never had any issue with my 225/45/17 tires.

So OUT the 225/40/18 and IN 225/45/18. New Bridgestone RE970AS for me.

My car is seriously lowered (garage basically said 'don't come back', 90% of them have issues raising it... thanks I had my racing jack in the trunk).

I had concerns about rubbing. It is a close call *but they don't rub*. It was a gamble.

What I didn't expect is that high tire walls accentuate the effect of lowering, esthetically. Very happy with the initial results.

Good to hear!
No problems rubbing on the inner fender well?
any pics??

[will.c]

Originally Posted by ichibanumba1

Thanks for the pics!
What offset are your rims?

it was 17x7.5 ET20 all four sides. ASA JH-3 wheels.

[Saintor]

Originally Posted by ichibanumba1

Good to hear!
No problems rubbing on the inner fender well?
any pics??

Here we go.





BTW, I got my handling back. My Conti WinterExtreme tires were terrible, handling-wise (I should have bought at least H-rated tires - mistake).

[Tom K.]

[quote=ichibanumba1;11638606]Thanks! Would you know how far off the speedo calibration would be?
Would speedo reading 61-62 mph and actual speed be 60 sound about right?

It depends on your current speedo error - which varies from BMW to BMW. Check your speedo at a true 60 MPH with a GPS and subtract about 4.5%. The result will be your reading @60 with the larger tires.

For example, if your speedo currently reads 64 mph when you are going a true 60, then it should read about 61.2 mph with the new tires.

Tom

[Beas]

i feel like the tires are kinda tall on this car to begin with. going another inch higher will give u the 4x4 look imo. Its all owner preference and ive always felt that lower is better. Im actually switching to a slightly shorter tire just to get a little more clearenece and to be able to ride lower.

if u dont give a shit about ride height than the only real difference would be speedo. you would have to be real carefull if u tend to speed a bit already. you would think your doing 57 in a 50 but u would actually be going a few mph faster.

Originally Posted by Saintor

Here we go.

Looks good!

I did the same, going with a 245/40/18 all around. It really helped to eliminate some of the wheel well gap, given my non-sport suspension sedan, and I gained a half an inch of ground clearance as well. Super happy with the results.

[VMRWheels]

You should be fine by increasing the profile by only 1 size since you're not lowered.

[ichibanumba1]

If I went wide with say 10" wheels et 37 and 265/35/19 in the rears, think I would have any problems? I'm looking at my current rear fenders and it looks pretty tight... I'm willing to roll my fenders if I have to...

Also, anyone have problems with tpms in this case?