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[emesdub]

Like the title states, what's the optimal tire sizes for the following setup for an E92 M3:

F 20x9 ET20
R 20X10.5 ET26

The car will be dropped on H&R sports. I don't want rubbing, and don't want to roll the fenders either. Looking for the ideal street setup--with occasional track use. What do you guys recommend?

[Lemans_Blue_M]

Originally Posted by emesdub

Like the title states, what's the optimal tire sizes for the following setup for an E92 M3:

F 20x9 ET20
R 20X10.5 ET26

The car will be dropped on H&R sports. I don't want rubbing, and don't want to roll the fenders either. Looking for the ideal street setup--with occasional track use. What do you guys recommend?

If by 'optimal' you mean the tire sizes that will square up with the outer lip of the wheels (providing some rim lip protection in the process) then here is what I suggest for your wheel setup listed above:

255/30/20 for the front

295/25/20 for the rear

These will be the perfect tire sizes for your new wheels. Anything more will be overkill IMO.

[isugoo]

Originally Posted by Lemans_Blue_M

If by 'optimal' you mean the tire sizes that will square up with the outer lip of the wheels (providing some rim lip protection in the process) then here is what I suggest for your wheel setup listed above:

255/30/20 for the front

295/25/20 for the rear

These will be the perfect tire sizes for your new wheels. Anything more will be overkill IMO.

That'll be one tough size to fine.
FYI:
It would be the IDEAL to match stock diameter.
245/35/19 Diameter: 25.8
265/35/19 Diameter: 26.3

255/30/20 D 26.1 (+.3 inch larger than the stock) - optimal wheel width: 9
295/25/20 D 25.9 (-.4 inch smaller than the stock) - optimal wheel width: 10.5

So in stock setup, rear diameters are larger than the front.
But with 255/30 and 295/25 setup, your front diameters are actually larger than the rear.


Go to E90Post wheel section to use calculator or tirerack for overall diameter specs.

I was looking for (actually still looking) same size wheel setup (CH-R) but had a hard time matching the tire diameters with optimal tire width.

Good luck.

[Lemans_Blue_M]

Originally Posted by isugoo

That'll be one tough size to fine.
FYI:
It would be the IDEAL to match stock diameter.
245/35/19 Diameter: 25.8
265/35/19 Diameter: 26.3

255/30/20 D 26.1 (+.3 inch larger than the stock) - optimal wheel width: 9
295/25/20 D 25.9 (-.4 inch smaller than the stock) - optimal wheel width: 10.5

So in stock setup, rear diameters are larger than the front.
But with 255/30 and 295/25 setup, your front diameters are actually larger than the rear.


Go to E90Post wheel section to use calculator or tirerack for overall diameter specs.

I was looking for (actually still looking) same size wheel setup (CH-R) but had a hard time matching the tire diameters with optimal tire width.

Good luck.

I matched those tire widths and rolling diameters very carefully. (taking a number of factors into consideration)

Those sizes aren't perfect, but they do provide him the proper clearance, rim lip protection and a rolling diameter within the 2% margin of error. (speedo)

245/30/20 offers slightly better rolling diameter, but at the expense of skinnier tires that offer less rim protection and are slightly stretched for the wider 9" wheel width...

I would have suggested 305/25/20 for the rear tires, but the wide wheels + offset + lowered on H&R springs might cause rubbing issues on such a wide section width tire.

It's not at all important to match the front and rear tire diameters exactly. Just as long as you don't get too far away from that OE baseline.

I put a lot of thought into this, and I assure you my recommendations take everything into consideration.

It's a delicate balancing act.

[emesdub]

thanks for the help. the tires i'm looking at aren't available in 295's, would these sizes work as well?

255/30/20 and 285/30/20

[Lemans_Blue_M]

Originally Posted by emesdub

thanks for the help. the tires i'm looking at aren't available in 295's, would these sizes work as well?

255/30/20 and 285/30/20

285/30/20 is really pushing it (26.7" rolling diameter), but you might just have enough clearance to get away with it. It will be close as far as overall diameter is concerned.

If this is your only other option, then I would reconsider the 305/25/20 (26.0") before buying the 285/30/20 tires which are too big...

20" tire sizes are very limited.

[islandsnow]

if your looking for like new 2 front tires in Toyo (only 100 or less on them) I have a pair for sale

http://www.m3post.com/forums/showthread.php?t=262628

[isugoo]

255/30/20 and 285/30/20 would work (and easier to find the tires).
Either that or 245/30/20, 285/30/20 will be my choice
but 245 on 9" wheel will be kinda stretch look that I don't really like.

[askiles]

Originally Posted by Lemans_Blue_M

If by 'optimal' you mean the tire sizes that will square up with the outer lip of the wheels (providing some rim lip protection in the process) then here is what I suggest for your wheel setup listed above:

255/30/20 for the front

295/25/20 for the rear

These will be the perfect tire sizes for your new wheels. Anything more will be overkill IMO.

I would go with this same tire setup as well. Well done!

-Andy

[SCCAForums.com]

I learned the hard way... different tire manufactures have different 'measurements' in what they consider a 255 or a 285, 295 etc...

To get closest to 'stock' Diameter, (height not width) I believe the 255/30/20 & 305/25/20 are the ticket. Especially in your case, with a 10.5" rear wheel.

I went through three sets (in 2 weeks) until I was able to get it right... PM me your email... and I can send you some 'larger' pics... showing the difference of 255 & 285's vs. 255 & 305's.

If you are going to go the 285's.. Yokohama S. Drive made a VERY big one... that fit on my 10.5" rear wheels great... But I didn't like the 'street noise' (when cornering spiritedly).

So, I then tried Bridgestone RE050A... which was PERFECT on the front... but their version of the 285 was almost a full inch narrower, and 1/4" shorter than the Yokohama... (It looked like a '78 Dropped Cutlass!)

I finally just ended up biting the bullet and purchasing the Michelin Pilot Sport PS2's, and went to the recommended 255/30/20 Front & 305/25/20 Rear.

If you lower your car... I've heard the 255's up front will rub... so you may need to run the 245's. I think if you run the 295's in the back... it could look odd... as that tire is about 1/4" lower than stock... and would be awfully stretched on the 10.5" rim (if depending on the tire manufacturer, doesn't size up well.)

If you attempt to search the 'actual' Tire Brand websites (Yokohama, Michelin, Toyo etc...) you can view the 'actual' tire specs... to compare which are sized bigger and smaller.

Enjoy!
Dave

[askiles]

I once had this setup, lowered on H&R springs, with no rubbing:

20" x 9" ET20
20" x 10" ET25

Toyo Proxe 4's
295/25/20
255/30/20

It looked really good too. I believe Toyo's tend to look thin.

-Andy

[Vic55]

I run:

HRE P40
20x9
20x10.50
both et28

255x30 and 285x30 Nitto Invo... the Invo has a smaller sidewall and I have zero rubbing and Im dropped on RD sports (1.25 front drop and .9 rear). They drop the car more than H&R. Im sure if I ran PS2's Id rub.

[TwistaStick]

I am also running 9x20 on 255/30/20 and 10.5x20 on 285/30/20 wrapped in Nitto Invos. I'm not lowered but it looks perfect to me. No rubbing.