New Wheels & Tires
Before we get into this post, I want to apologize in advance - I was a bit tight on time today and some of these iPhone photos do not live up to the standards I am aspiring to bring to this community. I will endeavour to redo some of these photos with my DSLR when I have a little more time.
Tire Rack was kind enough to drop off some awesome new shoes for the 1er!
The wheels are
Kosei K8R finished in the "Light Grey Painted" finish. The specifications from Tire Rack are 17x9" +45 offset at 16.95lbs and can be found by looking at wheels for a 128i at Tire Rack (they are listed as a rear fitment but I have ordered 4x for use front & rear). They are $199usd each brand new.
The tires are
Bridgestone RE71R in 255-40-17 at $189.21usd each. First impressions when you touch and see these tires are "WOW!" They look and feel a lot more like a Toyo R888 race tire than the Bridgestone runflat street tire they will replace. They are SOFT and the tread depth is very shallow - these are definitely competition street tires.
Let's get this out of the way early - these wheels/tires are a LOT wider than the stock wheels that they are replacing. The stock wheel on my 128i is the same front and rear - 17" diameter, 7" width with an ET47 offset. Great candidates for mounting winter tires, but not much else... The stock tire is an equally uninspiring 205-50-17 Bridgestone runflat all-season. The image is a bit hard to see, but I estimate the total mounted section width of the tire at around 8 3/8".
The new wheels are the same diameter but that's where the similarities end. They are a full 2" wider at 9" width with an ET45 offset.
In terms of clearance, mathematically the new wheel extends 23mm further inboard (where there is still lots of room even after this) and 27mm further outboard which is a lot tighter. The reality is the tire will require even more clearance than that. While the new tire is a "255", these are about as wide as a 255 will ever run and looks visually
perfect on a 9" wide wheel with sidewalls approximately square. When I measured it, the fully mounted section width appears to be about 10 1/8". Afterwards, I stacked the 4 wheels/tires and measured from the ground and came out with 41" even, which would reflect 10 1/4" per wheel/tire.
The good news is that despite this massive increase in wheel/tire size, we are still losing a considerable amount of weight - 6.2lbs per corner, and rotational weight at that! Tire Rack indicates the wheel should be 16.95lbs and the tire should be 24lbs or a total weight of 40.95lbs. With my scale coming in at 42.6lbs, we have a 1.65lb discrepancy - hard to attribute to just a couple wheel weights and a valve stem and centering ring, but without having weighed them separately, impossible to determine where the inconsistency is. However, weight loss is weight loss, and the grip difference with these wheels/tires is going to be absolutely mindblowing.
I didn't test fit the wheel on the front as it will require a spacer, which will have to wait for the new coilover to determine. However, there was no theoretical reason why it wouldn't bolt onto the back, and bolt on it did.
No spacer required, included centering ring worked perfectly, and stock bolts were totally adequate. From this view, it looks like fitment is a piece of cake... However, sometimes looks can be deceiving.
At stock ride height, it's honestly a bit hard to make any obvious conclusions. I suspect on stock suspension and stock ride height, it would probably work just because there is so much wheel gap.
However, looking at it straight down from the top, it's immediately obvious that this bad boy is going to be tight when we get down to a more realistic ride height. We will need to do some more investigation once the coilovers arrive, I am sure that at minimum we are going to need to roll these fenders, and possibly increase camber a little bit.
I also received some new Hotchkis swaybars courtesy of Bimmerworld this weekend, I will dive into those when the coilovers arrive.
Mark