[basserk]

Thanks for all the detailed info, Electrc109. I'm not well-versed in translating offsets visually, so I'll have to study your numbers here. But yes, ideally I'd rather not use spacers, but I'm concerned that they (BMW) didn't list wider wheels/tires as recommended replacements. The kit adds about an inch up front, and about 2 inches or so in the rear quarters. I'd want my tires to be flush with the edge.

[Electrc109]

I have a big paper I am working on (only 2 weeks left in college), and either when I'm done with the paper or I need a good long break, I will make a chart showing the relationship between offset, rim width, and tire width. I expect to have completed a chart by Friday evening.

It might be a good idea to add spacers in the rear only since the arches are wider in the rear. The obvious option would be to have wider tires (possibly wheels too) in the rear, which I believe would increase understeer (it actually decreases oversteer, but MINIs slightly understeer stock). Spacers in the rear (in contrast to an inch wider tire) would have a smaller effect on handling and provide the same profile.

[obehave]

Quote: Originally Posted by basserk

Thanks for all the detailed info, Electrc109. I'm not well-versed in translating offsets visually, so I'll have to study your numbers here. But yes, ideally I'd rather not use spacers, but I'm concerned that they (BMW) didn't list wider wheels/tires as recommended replacements. The kit adds about an inch up front, and about 2 inches or so in the rear quarters. I'd want my tires to be flush with the edge.

I'm running 215-50 16s on stock X-Lites. 50mm positive offset.
They fill the stock holes quite well.
235-40 17s would get you some monsters but I'd start worrying about hydroplaning. That and when I turn mine full lock I have a fingers width between the outer edge of the tire and the fenderwell liner. Go wider with the same height/diameter and you'll shrink that. Go shorter to help that and you'll then have a big upper gap and you'll want to lower the car

I've never read that there were hub differences between the cars so considering that some of the stock rims have a 45 mm offset you could probably safely go down to 38 - 40.
7.5 inch rims would work.
All this will push your sidewall out about an inch.
Of course this is all guesstimation.

[Electrc109]

I'm not exactly a pro with excel, and I think I got everything right.

the offset is on the left and the width tire is on the top.
the red numbers correspond with the 15 inch profile and the blue numbers correspond with the 16 and 17 inch profiles (which are millimeters w/in each other)




and here is the actual .xls file

[basserk]

Here's another resource that might complement your work:
http://www.gmpperformance.com/produc...res/wheels.htm

Now given all this data, what offset would you recommend to suit the wide flares kit? Assume 2" and 3" flare widths, front and rear respectively.

[Electrc109]

add 25.4mm per inch with a change of tire width and offset. Stock, the 15 inch wheels have 42.5 mm from the wheel "hub" (the round piece of iron on the brake rotor where the lugs stick out) to the outside of the tire. I you add 2*25.4 and 3*25.4 respectively, you need a total amount of 93.3mm and 118.7mm chunck of tire from the wheel "hub." By looking at the graph I made, you find the numbers in the middle of the chart closest to what you are looking for, and pick the tire width and offset that would coordinate with the profile you are looking for.

Previously basserk had said that the flares were only one inch in the front, and two in the rear. this extra inch changes things drastically. The colored group of numbers that run diagonally correspond with the one inch adjustment.

My unprofessional opinion is that you would need a 225 series tire in the front with a positive offset of about 18mm and a 255 series tire in the rear with the same offset or a 225 series tire with about a -5 offset (or a 1 inch wheel spacer with the same wheel offset in the rear). Well, as for rim width, 7.5 or 8 inch wide wheels would suffice, and I believe there is a chart on tirerack's web site to help with that decision making. I will try to find it next time I need a break.

Your best bet is to use my data to get an idea about what you want, and ask a wheel shop if you can test a set to see if they would fit on your car. A good shop would most likely allow you to do one wheel to check for any tire rub when turning.

****JUST TO NOTE, I KEEP ON SECOND GUESSING MY DATA. PLEASE DO NOT BUY ANYTHING WITHOUT HAVING SOMEONE WITH PROFESSIONAL KNOWLEDGE CONFIRM YOUR DECISION. A 2 INCH CHANGE IN THE WRONG DIRECTION WOULD BE A TERRIBLE MISTAKE!!!

[obehave]

You have to be carefull. If you change the offset too much you'll drastically change the load on the hub. This always promotes early bearing wear.
I specced the 235 series above because it has the same diameter as a 215 - 45.
That and changes changing you offset to 35-40 will push you out an inch.
Since the width of the flare measurement has changed that impacts the decsision making. I really think that dimension needs to be nailed down positively. Exactly how much wider than stock needs to be established. That's your baseline, gotta have it.

[basserk]

I just uploaded a few pics with relatively exact (oh the irony!) measurements of the front and rear flares... Please check my gallery and see what you think:

http://www.mini2.com/gallery/persona...ery_14375.html

[Electrc109]

D = 1/2(T - t) + (O - o)

D = the distance you want the outside part of the tire to change from stock to aftermarket.
T = the aftermarket tire width
t = the stock tire width
O = the aftermarket offset
o = the stock offset

the rim width should correspond with the tire width and however you want the rim/tire combo to look.

any questions?

[minimaster]

Nice!

[obehave]

I'm with Electric109 on this; do not use wheel spacers.
8" rims is overkill. 7.5s should do unless you want to go over 235.
Like I said, I'm running 215s and they look pretty nice. 235s would look huge.
Remember you have the potential for adding considerable weight per corner compared to your current 15s.
Judging from your pic I would not try to get all the way to the edge of those flares.
For one thing they angle downwards and have a lip= scrubbing.
Having lived through the '70s "stick fat meat under your Chevelle and scrape the sidewalls" era I can assure you it looks goofy and is dangerous.
Once again, too far out and the load on your hub bearings will be detrimental to their health. If they fail it'll be detrimental to your health.
235 on 7.5" rims with a 40mm offset will get you a nice look.
What none of us know yet is what kind of clearance you'll have. Even though the flare is wider the original sheetmetal is still the same. My 215s at full lock comes quite close to the inner fender liner.

Tire choices

Just some random ramblings

[Electrc109]

Quote: Originally Posted by obehave

Having lived through the '70s "stick fat meat under your Chevelle and scrape the sidewalls" era I can assure you it looks goofy and is dangerous.

How about the '90s where 13" wheels and a horribly negaive offset was cool!!!

Quote:

Once again, too far out and the load on your hub bearings will be detrimental to their health. If they fail it'll be detrimental to your health.
235 on 7.5" rims with a 40mm offset will get you a nice look.

If half your change in tire width equals your change in offset, the inside of the tire will be the same as stock. Although this is not crucial, over the years, your car will appreciate it. (it is also possible to have a tire that gets too close to the inside of the wheel well which might rub

Quote:

My 215s at full lock comes quite close to the inner fender liner.

you have the wide arch kit also?

[obehave]

Quote: Originally Posted by Electrc109

How about the '90s where 13" wheels and a horribly negaive offset was cool!!!

Great pic!
Definitely worse than L60 15s squeezed into e 60 sized holes.

Quote: Originally Posted by Electrc109

If half your change in tire width equals your change in offset, the inside of the tire will be the same as stock. Although this is not crucial, over the years, your car will appreciate it. (it is also possible to have a tire that gets too close to the inside of the wheel well which might rub

Exactly. Well said.

Quote: Originally Posted by Electrc109

you have the wide arch kit also?

Sorry no.
I was trying to explain that at a stock diameter ( my 215-50s are within a 10th of OEM 195-55s) a wider tire comes closer to the inner fender liner. Not the fender lip or skirt but the liner or fender well if you will.
Going very wide and keeping the stock diameter may actually touch the liner especially during a load like hard cornering. Especially with passengers in the car.
Most of the folks here that have gone to wider have also gone shorter. That may be why we haven't heard of any issues. That and 225 is the widest I recall anybody putting on.

Fun thread

[Electrc109]

I think that car's name was the green monster. My friend sean bought it so he could get to work while he swapped a 350 in his isuzu pick-up. The car recieved donations from friends (hence the lime green paint). The thing wound up with 4 JL 10s in the trunk, green and purple crushed velvet interior (which was the thing to do back then), a sunroof from a junkyard....well, point being, the car was so horrible, you had to love it! =)

I have heard of people who either remove the wheel well liners when they lower their car. I don't know if this would be a good idea really, but its an option. Another possibility would be to cut the liner where you rub (drive the car for a few weeks, find out where it rubs, then away!), and if needed, add something to protect whatever the liner used to protect.

There's so many options I have in mind. I had a friend who actually reinforced her suspension in her '91 Civic hatchback when she put 'inverts' on her car. She also had airbags, so reinforcement was imperative (ironically, not many people actually did reinforce their suspension in such a case).

[basserk]

Based on all your great input, I think I'll go out and try this setup:

- 215/40/17 on 17x7 on front
- 235/40/17 on 17x7.5 on rear

The offsets will be a tough issue still because of the wider rears - They're not very common (at least on the styles I'm favoring) to have varying widths... i.e. many only come in 7.5 then it jumps to 18" sizes... argh. In any case, I have a lot more to go by than when I started looking -- so kudos to you guys! I'll be sure to post photos of the final choice and specs... wish me luck!

[obehave]

Quote: Originally Posted by basserk

Based on all your great input, I think I'll go out and try this setup:

- 215/40/17 on 17x7 on front
- 235/40/17 on 17x7.5 on rear

The offsets will be a tough issue still because of the wider rears - They're not very common (at least on the styles I'm favoring) to have varying widths... i.e. many only come in 7.5 then it jumps to 18" sizes... argh. In any case, I have a lot more to go by than when I started looking -- so kudos to you guys! I'll be sure to post photos of the final choice and specs... wish me luck!

IMHO running 2 different size tires is just a bad idea.
The whole thing about the MINI is balance and handling. You'll be tossing a good chunk of that out the window.
Bigs and Littles on a FWD car is just not right.

[KJ_daGreenMini]

but wont wider tires increase handling on corners by reducing the risk of the back end sliding out? there must be some advantages, perhaps on drag tuned jap cars, but maybe not on the mini?

[obehave]

Quote: Originally Posted by KJ_daGreenMini

but wont wider tires increase handling on corners by reducing the risk of the back end sliding out? there must be some advantages, perhaps on drag tuned jap cars, but maybe not on the mini?

The MINI understeers by design. If you're into something bad enough that you're losing rear traction you have problems wider tires aren't going to help

Drag tuned FWD cars actually run narrower tires in the back, less rolling resistance. Same reason RWD drag cars run narrow fronts.

[Electrc109]

this may seem kinda goofy but when considering handling, i suppose it would be best to have wider tires in the front than in the back (for traction), an offset in the back to match the profile of the wider tires in the front, with reinforced (or replaced) control arms on the rear suspension.

In result, you would have a big patch of rubber in the front to compensate for FWD understeer tendencies (or wheelspin if you have a real monster), and slightly smaller patch of rubber in the rear (w/ narrower rims of course) to reduce weight and minimize rolling resistance.

I think I've passed the point of diminishing returns in theorizing wheel/tire/offset changes!!! =)

p.s. I've finally completed that paper I was working on when I started this thread!

[obehave]

Quote: Originally Posted by Electrc109

this may seem kinda goofy but when considering handling, i suppose it would be best to have wider tires in the front than in the back (for traction), an offset in the back to match the profile of the wider tires in the front, with reinforced (or replaced) control arms on the rear suspension.

In result, you would have a big patch of rubber in the front to compensate for FWD understeer tendencies (or wheelspin if you have a real monster), and slightly smaller patch of rubber in the rear (w/ narrower rims of course) to reduce weight and minimize rolling resistance.

I think I've passed the point of diminishing returns in theorizing wheel/tire/offset changes!!! =)

p.s. I've finally completed that paper I was working on when I started this thread!

The bis and littles is only for drag cars though.
I definitely wouldn't try it for track/auto-x stuff.
We have some pretty talented auto-x guys that post here and I've never read of them using different size tires. Should be a good indicator for best practices.