Hi all,

My R56 is coming in later this month and am wondering if anybody is willing to share their thoughts on the 215/40 R16 Kumhos vs. the 225/40 R17 Hoosiers. I understand some people might not want to share this info, but if you are willing to give impressions of the two, I'd appreciate it. The main reason I ask is because I can probably only afford to go one route. Alex at Tirerack assures me that the 215 is the way to go, cheaper too, but I keep reading about wheelspin issues with the R56's low-end grunt.

Thanks for any info!

 

I'm a firm believer in making big rubber work. More rubber, IMO, is worth the initial change in ride firmness or handling, that can be dialed out. The more rubber the faster a car will be overall. Unless Alex has some hard numbers, he's depending on some old R53 data.
d

 

Thanks for your input. I agree with you about Alex. I'm not sure how much testing the Tirerack has done on the R56. No offense to him at all, but the impression I got from him was that they tested the R53 and the '07's weren't any different.

Anyway, do you know if 225/50R16s fit in the R56? I'm actually considering going that route, especially if people are spinning their tires even with the 17's. Thanks for the opinion.

 

I just had another thought... Has anybody tried to fit 245/45R16's on a R56? I just noticed that Hoosier recommends 7-9" rim width. I can't imagine it would fit without rubbing, but I thought I'd ask anyway. I imagine the wheel would just pinch the tire and bow it out? Hmmm...the things I'd try if I were independently wealthy...

 

Are the 16s a 16x6.5"? If so, I think it would be a struggle to fit 245s. I've tried in the past!

d

 

Yes, 16x6.5

 

Well, after more digging, I still don't know whether or not 225/50R16's will fit. Some threads have people saying that they will fit... I called Tirerack and they were pretty adamant about them not fitting. In fact, the salesman sounded kind of pissed off when I told him some people had said they would fit. Meow!

Anyway, any more input would be appreciated. With a spreadsheet I made up real quickly, it looks like the 225/50R16 has 5mph more in 2nd gear than the 215/40R16. That's pretty significant. Though, I suppose a downside is that the car would be riding a full inch higher with the 225 16's vs. the 215 16's...

 

funny, because Woody@tirerack.com ran that size on his car when his wife won GSL at Topeka in 2005.

Per

 

i'd think that the 225s would have absolutely NO problem fitting! Is it really a full inch higher? I'd still put them on but that's me. I'm one that believes that more rubber is better overall and would try to dial out any mishandling characteristics that it could bring.

d

 

Yes, the 225/50R16 OD is 24.7" and the 215/40R16 OD is 22.6" for the Kumhos. That's for an unloaded tire, I believe. It's still close to a 1" ride height difference, though. The advantage is a wider tire. Other disadvantages are weight and large sidewall.

Per, I got to see you guys run in Milwaukee this weekend. I was told you were a great guy to talk to, but I didn't want to bother you guys in grid. I noticed a lack of Kumhos there. Do you mind sharing your thoughts on the 215? Understandable if you don't want to. I'm not sure if I can come close to you guys when I get my R56, but I'll try. My plan right now is tosee what the kumhos will do first, and then go to hoosiers. Especially since Craig mentioned in his post that he corded his A6's in 19 runs!

 

I like the V710s, but don't think they put down the power well enough for a Gstock car. The Hoosiers are a lot better at that. The problem is, the car still has issues with wheelspin and really needs more footprint, in my opinion.

On the other hand, Craig sure smoked us on the 16-inch Hoosiers.

 

That's interesting, because at last years Wendover Pro, the 710's seemed to do better off the line and the Hoosiers did slightly better in the turns. All in all, they're VERY closely matched IMO.

 

225/50R16s fit on my R53, so I'm sure they'll fit on the R56...

All I had to do was trim the rear fender flares a little bit to ensure zero rubbing in all conditions ; )

 

Was that a 225/50R16 race tire or street tire? Also, do you know the offset you were running? Thanks for the info.

 

I just switched from V-710's to A6's. I gotta tell ya the A6's seem to have grip out the wazoo. Turn in is much crisper and the car sticks much better in sweepers. Of course thats just my opinion, YMMV.

 

I am fairly new to the Mini world of competition, but I have been running Solo for years. I have an older R53, and on the advice of people on here, I went with 215/40R16 V710s on some Rota 16X6.5s.

After wearing out 2 tires pretty quickly, mainly from wheel spin, I bought 2 225/50R16 V710s. The wheel spin issue is MUCH improved, but the gearing change is less than ideal. There is improved grip in the front, as well.

So, I am running 225/50s up front, and 215/40s out back. I have absolutely no fitment issues.

All of that being said, I think that I should have gone with the 17" combination, and used 225/40R17 Hoosiers up front, and I would think that if I could get the 225s to fit out back that would be ideal, and if not, I could run 205/40s.

We run much smaller courses here in Canada, and go down to 1st gear often.

 

Have you tried putting your 225's on the rears to see if they rub at all? After reading all the posts, it seems that most people 'feel' that the 17's are faster. After seeing the Milwaukee NT, I was convinced the 16's were quicker....BUT even OasisT (who won--congrats and well done, btw) has mentioned after the tour that he thinks the 17's are quicker. I wonder how close he could have gotten to Bartek had he run the 17's...

I've decided I'll just go with 16's for now w/the 215 Kumhos as I get familiar with the car. From there, I'll have to try for myself like everybody else to see what I like. I'm wondering if your staggered setup would work. One question for you is do you notice the front end of your car sticking up compared to the rear? The whole front end of the car should be 1" taller than the rear w/225/50 vs 215/40...

Thanks all for the comments!

 

I have 205 45 16 A6s and after the peru tour and a couple local events the hoosiers are almost gone. A total of 19 runs. They have tons of grip no doubt about it but I don't have the funds to keep putting them on my R56. I am thinking of going with the 225 kumho. We will see how they do. I will be at the toledo pro end of july.

 

19 runs on the A6s? Have you rotated them front to rear each event? Have you flipped them on the wheels (remounted them) so the inside edge is now on the outside? I'm getting about 50 runs out of my 225/40x17 A6s on my Mazdaspeed Protege. That isn't corded but it's getting pretty close to it. Suspension specs are about -0.6 camber up front, about -0.9 in back, so somewhat similar to the Mini.

(Hi John! I'm looking at an R56 for '08....)

 

I have not bothered to see if they will fit out back. I expected that rear tire wear would be awesome, and that my old 215s would last forever in the rear. If I was always going to have some 215s around, why put the 225s in the back? That is only going to increase rear grip, something that my car does not need. However, going with the small front bar sure has helped the balance, and rear tire wear has gone up. Still, I figure I will always run a stagger. I have been told that 225s hit the flares in the rear, but I do not know from personal experience.

The front is definitely more full than the rear, but I have no issues.

 

Hey Ray:

Yeah, CCG was my first time on Hoosiers and I was shocked how different they drive. I'm not convinced I like them any more than my 710s. On the flip side, I certainly didn't like them any less. They're different. I do know that my wallet likes the longevity of the 710s more.

I'm going to run them again (after a flip) at NCAC and then figure which tires I'm ordering for Topeka.

 

This is a re-post from another thread that is somewhat on point. I thought it might add to the discussion.

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As a rule of thumb (with all other factors being the same) . . . the smaller and lighter the wheel the better. Less centrifugal mass means faster accleration and quicker braking. It also means better turn-in and thus, better handling.

Newton's second law of motion . . .

"The more mass the object has, the more inclined it is to resist any change in its motion."

The trend to bigger wheels is all about looks . . . not performance. Smaller diameter wheels mean lighter tires as well. The benefits of running the smaller wheel can be substantial.

I think this accounts for much of the difference in the lap times you discussed. Your benefit is not only lower weight . . . it's also the 'moment' of the weight. Your weight is closer to the center and requires less energy to accelerate or to stop.

Example: Swing a ball on a string above your head . . . the longer the string, the more force it takes to swing it, even though the ball weights the same.

The only real reason to run a larger diameter wheel is brake size and cooling (maybe looks ?). But, some of the benefits of larger brakes is reduced by the extra force it takes to slow down the larger rotational mass and weight.

Can anybody say . . ."inboard brakes"? . . . that would be nice, small wheels, big brakes.

Lastly . . . remember, there are 4 tires on the car. Most of the benefit is in the drive train but the lower weight at the rear is a benefit too. The same laws of physics apply to the rear wheels.

My 2 cents . . .

Randy

 

Sure, but if you're a hardcore SCCA stock class autocrosser, you're going to want to stuff as wide a R-compound tire as possible under the car on its stock sized wheels. 225s or 235s are available and fit on the 17x7s vs 205s and 215s w/ the 16 x6.5s. It's been proven again and again that the fastest R-compound tire size for a stock class car is the fattest one you can fit on that rim, irregardless of the rim's width. For example, 225s can and have fit on a 5-inch rim, and won multiple national championships. Grip is king.

Plus, you get a slightly taller tire, which helps at the top of second gear, keeping you from having to shift to third on faster courses.

 

I run Hoosiers, 225-45/15's with a 8.7" inch tread on a 15 x 8 inch wheel. The tire is identical in evey way to the 17" Hoosier except in overall height and diameter. I think that is about as fat a footprint as you can possibly put on a Mini. As a comparison, the 205-40/17 RA1 Toyos have a 7" thread.

There are other benefits. The lower diameter tire fits the car's geometry better. The car is effectively lower without shortening the suspension which causes the a-arms to invert which in turn screws up the bump steer.

In addition, the shorter diameter tire improves the overall gearing by reducing the final drive ratio. The 2nd to 3rd gear comment may apply in some cases but is no reason to sacrifice the other benefits.

The 15" tires weight 1.2 less than the 17's and the 15" wheels save another 2.6 lbs . . . 3.8 lbs per corner of unsprung weight.

http://www.hoosiertire.com/grandamc.htm

What's not to like about that? You may like the looks of the larger wheels and tires, but performance is improved with the smaller ones.

Again . . . just my 2 cents . . . take it for what it's worth.

 

The problem lies within the fact that we are discussing a Solo stock class which doesn't allow a 15x8 wheel. maximizing tire width is key in Solo and the largest available is with the 17x7, largest available size for the R56.

d