I'd want to see all the details on that analysis to be convinced. For example, for each 15 and 16 set up: wheel and tire weights, overall diameters, what car was used, weight of the car, upgrades on the car such as suspension, etc. Yes I'm sure that under certain conditions, a 16 set up can beat a 15 setup, but I wonder about all these conditions and the car. The MINI is unique when compared to other cars. Just my 2 cents. What's wrong with lighter AND wider AND shorter if you can get it (or as close to it as you can get)?

 

Carlos,

If you follow your reasoning regarding contact patch, would you choose to run the 17" wheel on the MCS? For example, Kuhmo makes a V700 in 205/45-16 and 205/40-17. They are almost identical in overall diameter, and the 17" tire is 2/10ths wider in section width. If you ignore wheel weight, this would be your largest contact patch, right?

cincymcs

 

Cincy-

I'm undecided on the 17s. I would say no mostly because I have a feeling You would destroy the outside edge in two runs. Low profile tires (less than 45) tend to not due to well on camber challenged cars.

jazmini-

If 15s are soo much faster why aren't the big name National level Mini autocrossers running them? Like I said before, Garfield and Chiles all run 16s and those two might actually know a thing or two about autocross. Keith Brown already gave us empirical evidence showing that 205/50/15s mounted on stock wheels are 3/4" narrower than 205s on the stock 16s. I don't know what school of thought you subscribe to, but for most of us in autocross less tire = less grip = slower times = you lose.

 

I'm just saying there are a lot of variables to consider, and I'm not convinced. I'm not saying you are wrong, just that I'm not convinced, and my personal feeling is as I've stated. I just read a post on these racing forums where someone said that the MC was helped a lot by lower gearing from shorter diameter tires as it really gave it a boost coming out of the corners. :smile:

 

There is no "Lower Gearing" related to the 15's... The diameter of the 205/50/15 Kumho 710s and the 205/45/16 Hoosier A3S04s are essentiall the same.

 

OK now you're switching variables, as the 45 series vs 50 series. Yes, I agree that the 45 series will give faster turnin than 50 series. If that is what the winners are using, then I see now. But you will still want to keep weight down as much as possible. :smile:

 

Low weight is nice and all, but I'd give 2-3 lbs a corner to run 6.5" wide wheels instead of 5.5" wide wheels any day.

 

So, are you saying its better to run 205/45/16 or 215/45/16 on 6.5 inch wheels versus 205/50/15 on 5.5 inch wheels? And are you talking stock wheels or aftermarket lighter wheels? Because stock 16 inch wheels are heavy, i.e., 20 lbs.

 

There are no 205/50/16 race tires... You have to use what is available when making comparisons.

Remember everyone this is the H Stock forum... we have to keep the stock rim widths 15x5.5 or 16x6.5.

 

Keith, what are you racing and winning with -- is it 205/45/16s and in what tire and on what wheels? You must know what you are talking about and what works best for you, as you are a winner. And do you know why it works? Thanks.

 

I'm simply suggesting you put wheel weight in perpective. Lighter is not always better if it means compromising something else; in this case wheel width. By and large, the serious HS MINI driver will pay twice the price of a set of used 15" 8 holers for a set of Monzas that weigh about 2 1/2 lbs more per corner. The extra inch of wheel width is worth the 2 1/2 lbs PLUS $300.

Truth be told I ran 16" o.e. wheels last year and wouldn't have traded them even-up for a set of o.e. 15s. The extra width was worth 8 lbs in my opinion. BTW- I never lost to a MINI on 15s.


The current paradigm is that the 16s are better. All the evidence points that way. Until you provide some results-based evidence to the contrary , I'm not convinced I should care that you're not convinced. I wish more of my competitors would ignore all the existing evidence and run 15 x 5.5s.

 

I ran the Hoosier A3S04 205/45/16 on the NZO Monzas. I don't have the budget to buy a set of the SSR Comps. Well I guess I do but I have two sets of Monzas instead of one set of SSRs.

Locally I run on the 15's with 710's. You can't beat the price or wear. I am looking forward to the 215/40/16 710's to get the extra tire on the ground.

 

I see I see. So, it's best to have as wide a tire as possible with as much tire contact to the ground. Of course you are also using a very low profile tire ratio too, i.e., 45 series and possible 40 series, to provide quick steering. Weight is important, and you are not going too heavy, by using lighter aftermarket wheels -- in 16 inch diameter, but are limited to the OE wheel width of 6.5 inches. Also the lower gearing helps, i.e., with 205/45/16 at about 23.3 inches in diameter or so (depending on tire), which is less than the 24 inch OE. It all makes sense, and I've learned somethings. Thanks. Good luck all with your racing!

 

Good quote, worthy of framing. I like that. Thanks again and good luck!

 

Now you're getting it

Remember that in autocross ultimate overall grip is king. Trumping even the ability to accelerate.

Think about this scenario:

What will have a larger effect on a cars autocross times, a 3" gain in contact patch (going from 205/50/15 to 205/45/16) or a 1% increse in gearing?

 

In a thread in another autcross forum, one of the more knowledgeable autocross minds out there, Andy Hollis, said:

" Another way to look at this is through g-plots for autocross runs. I do these all the time. In general, I find that I am full on the throttle less than 30% of the time. Yet, I am cornering at the limit over 90% of the time."

So sacrificing a little acceleration with marginally heavier wheel/tire combos and/or slightly taller gearing is well worth it if you gain grip; you'll use the grip 3 times as much as the acceleration. There are some unquantifiable handling advantages of lighter wheels that factor in, especially on bumpy course, but in the end Carl is right; "grip is king."

 

Yes, that makes sense. I can see that grip trumps 0-60 times, as once you get going, you spend the rest of your time in all the curves. :smile:

 

The most important thing is to get the best tire for the job after that get the best wheel for the tire. If the best tire is available for both a 15" and 16" wheel then the best 16x6.5 wheel will be the better choice over the best 15x5.5 wheel because it will control the tire better. Say that you decide the Hoosier is the best tire but there is no way you can get the 225/45/15 tire on the car and be legal, so you're stuck with a 205/50/15 or a 205/45/16, GET THE 16. Now say brand X makes a 225/45/15 that will fit because it's nowhere near as wide as the Hoosier and you think it's at least as good as the Hoosier but they don't have any 16's in the same diameter wider than a 205, now you're stuck with tire testing.

Side note, many ppl think the best wheel for a given tire size is what the manufacturer lists in the tire specs as the "Measureing Rim Width" THIS IS NOT THE CASE. This is no where more evident than in Hoosier's tire spec's, which in some cases has a recommended rim width wider than the specified rim with range, to say nothing of it's measuring rim width. I find this very odd for the Hoosier but in any case if you have a choice in wheel width get the widest wheel that will fit the tire!!!! The Measureing rim width is only a standard by which consumers can compare tires.

 

Keith,
How would you compare the grip between the 710's and Hoosiers? Are the 710's giving anything away?

 

I did a quick test of the 710s versus the Hoosiers and the Hoosiers were about .2 faster on a 45 second course. both sets of tires were brand new. But the 710s were giving up 3 inches of contact patch... I think that when the new size is available it will be a very comparable tire. When equal sized tires have been compared the 710s have been slightly faster, especially in the Corvette sizes.

 

Rumor I heard was March for the 16". Is there any possible truth to that or is it wishfull thinking?

 

That may be optimistic... I heard April. but they should be available by mid season.

 

Here's a thought, and an option that has been untried since it's a pain in the ****:

Plenty of top National autocrossers, including Robert Carpenter and Chang Ho Kim, have run 225's on 5" wheels when that was there best option! That's right FIVE INCH wheels.
So having said that, does somebody want to try squeezing 225/45R15 Hoosiers on the 5.5" wheels with a 5mm spacer???

I'm gonna have to think that you still wouldn't gain that much contact patch, but it's worth a try...

Good Luck!

Brian

 

Carpenter managed to get the A3S03 to perform that trick, but I doubt that you could do the same thing with the A3S04, with the added steel.

 

That's not necessarily true given the bead "extender" on the S04. For example, with the S03 you needed a 9" wide wheel to have straight sidewalls on a 225. Now, a 9" is too wide, you're better with an 8.5" or even an 8". The extender allows the sidwall to sit more vertical.
The new construction might be an issue, but the bead would probably offset that.

Brian