245/40/17 on DS1's...

[L3R E36]

Hey guys, just had a quick question...
I recently got new 245/40/17 Dunlop Direzza DZ101 slapped on my DS1's.
I was running 235/40/17 Michelin Pilot Sport 2's (and clearly I would have loved to get those tires again, but considering I am running low on funds- I made do with what I had).
Now here's the thing, when I am on the throttle through a turn, it feels almost as though the sidewalls are flexing a bit more than they should ( feeling is comparable to under-inflated tires although they are all at 40psi right now). I understand that going from a PS2 to a Direzza, I am going to loose some of my turn in and stickiness, but is this feeling related to the fact that I am running 245/40/17 on a 7.5 inch wide wheel, allowing for a little more roll in the sidewall, or solely because the sidewalls are softer than that of the PS2's (or perhaps a mixture of the both). I am curious as to whether or not I can get rid of this feeling, considering it is somewhat unsettling when you get body roll from your tires. Anything helps, and thank you in advance for your responses.
Thanks guys,
Tyler

[reborn]

In my opinion, for a somewhat performance oriented setup, 245s are too wide for 7.5'' wide rims. 235s may even be a little too wide really, although a good compromise for daily driving.

I run 235s on 8.5'' rims, and the feel is much better.

Id guess that, as you've said, the feeling you're getting is a result of the tires bubbling around the rim. You'll get used to it after a while.

I have read that this "bubbling" does actually heat up the outsides (and insides) of tires, though....

[Dakar95matt]

I would agree that 245's are probably too much tire for a 7.5 rim. I am running 7.5f/8.5r and have 235's on the front and it looks like a bit too much on there. That being said my 95 came with 235's all the way around on 7.5s, I have 245's on the rear but that's on a 8.5 wheel.

[fatboycowen]

Funny, i was just about to pose a similar question, except i havnt done it yet.

I got a killer deal on a set of (4) 245/40/17 Kumho MX tires with like 80% tread left. I have staggered DS2s. Since it was a killer deal i have two choices. I could buy smaller front tires, and hope that the rears wear out faster then the fronts (or i could do burnouts...). Or, i could put these tires on all 4 corners.

For reference, i have autocross/track wheels, so these will be used mostly on the street, but the might make it to autocross or track if i am too lazy to swap them out...

Sorry to threadjack, but this seems relevant.

[joenationwide]

Funny, i was just about to pose a similar question, except i havnt done it yet.

I got a killer deal on a set of (4) 245/40/17 Kumho MX tires with like 80% tread left. I have staggered DS2s. Since it was a killer deal i have two choices. I could buy smaller front tires, and hope that the rears wear out faster then the fronts (or i could do burnouts...). Or, i could put these tires on all 4 corners.

For reference, i have autocross/track wheels, so these will be used mostly on the street, but the might make it to autocross or track if i am too lazy to swap them out...

Sorry to threadjack, but this seems relevant.

you could be lazy and just run the 245 MXs on 7.5" fronts and 8.5" rears. But on the front you will notice (just like the OP did) that the tires will feel numb, like on tires with low air pressure. I'd try to find another pair of rear DS2s and run em on the front. Or sell the DS2s and get some Kosei K1s. They're cheap at tirerack now. (Its a worthwile upgrade to run 8.5" all around). Hope that helps.

edit* you could always run the 245 MXs on your autox wheels and run in STU?!? :dunno

[91M5]

You are also likely getting a bit of tread squirm as the tires are brand new.

[fatboycowen]

you could be lazy and just run the 245 MXs on 7.5" fronts and 8.5" rears. But on the front you will notice (just like the OP did) that the tires will feel numb, like on tires with low air pressure. I'd try to find another pair of rear DS2s and run em on the front. Or sell the DS2s and get some Kosei K1s. They're cheap at tirerack now. (Its a worthwile upgrade to run 8.5" all around). Hope that helps.

edit* you could always run the 245 MXs on your autox wheels and run in STU?!? :dunno

Well, i have a set of Kosei wheels with 255 Azenis tires for autocross (STU or similar). These would primarily be my street wheels. I was close to a trade for 8.5 DS2s this winter, but it fell through. I am thinking i will probably buy new 225/45R17s for the front, and use 2 of the rear tires i bought used. I figure its still better then buying 4 new tires, as i only paid $150 for all 4 MXs.

[JETninja]

I will only add that my car was setup (the PO) by a NASA instructor and ran quite well and balanced after all the suspension tweaks with 245/40 all around on DSII's. (Dunlop R Cups that are closer to 255/40 in actual size, DSII front is 7.5") I have kept up with the theme with street tires and have "0" complaints. I actually went down one setting both front and rear sways to soften it a tad for the street, but it still drives with great neutrality and incredible responce. I am about to move to 255's on the rear because I do have serious traction issue with these tires (that do work well in all weather and decent mileage for my 70m daily commute) in 1st & 2nd when really jumping on it....

I am running more of a track setup as far as alignment settings go and I'm sure that helps....

Edit; You can read the PO's initial setting up of this here: http://forums.bimmerforums.com/forum/showpost.php?p=3969516&postcount=85

[reborn]

Funny, i was just about to pose a similar question, except i havnt done it yet.

I got a killer deal on a set of (4) 245/40/17 Kumho MX tires with like 80% tread left. I have staggered DS2s. Since it was a killer deal i have two choices. I could buy smaller front tires, and hope that the rears wear out faster then the fronts (or i could do burnouts...). Or, i could put these tires on all 4 corners.

For reference, i have autocross/track wheels, so these will be used mostly on the street, but the might make it to autocross or track if i am too lazy to swap them out...

Sorry to threadjack, but this seems relevant.

See if you can find a deal on two 8.5'' ds2s. That would be a good setup.

[fatboycowen]

See if you can find a deal on two 8.5'' ds2s. That would be a good setup.

Point me to it, and i would be HAPPY.

[L3R E36]

thanks for the insight fella's, any more input would be appreciated...

[reborn]

Point me to it, and i would be HAPPY.

Ill keep an eye out.