15 inch tires

[Jackal]

Hi team,

I have recently started preparing a new car for next season. I will be running 15 inch tires (225/45/15) square and wanted to ask opinions about tires in this size. The car is very light and may have issues getting to temp from what I have read. I figure i have such a great wealth of knowledge here to draw upon,  so why not ask? Surely someone has used this size here before.

It seems that RE71's are not an option for me, and I have a selection of unfamiliar tires to choose from. I will be running the tires on both street and on the parking lots. Tell me some thoughts on the tires I can see as options and any I haven't listed. I am listing options for both a 45 aspect as well as a 50 aspect.

Important details: Wheels are 15x8, Car is 2500 lbs MR configuration
 

Toyo R888 (the first obvious choice)
Toyo Proxies R1R
Toyo Proxie RA1
Hankook Ventus R-S4
Kuhmo Exsta V720
Nexen N FERA SUR4G
BFGOODRICH G-FORCE RIVAL
BFGoodrich g-Force Rival S 1.5
Nitto NT01
Pierlli P Zero
Yokohama ADVAN A048

[PedalFaster]

Why are you ruling out the RE-71R? It's available in 15" sizes, albeit only two of them.

If being competitive at autocross is a goal, your best choices from that list are the Nexen and Rival S. To my knowledge, they're the only tires on that list that have been driven to national championships. The Rival needs some heat to work, so the Nexen may be the better choice given your car's potential inability to generate tire heat. If I'm remembering correctly, the Nexen's not very durable, but that won't be that big a deal on a 2,500 lb. car on 8"-wide wheels.

Several of the tires on your list are "R-compound lite" tires designed for dual street/track use: R888, RA1, NT01, and A048. They'll all need some heat to work best, plus none of them conform to the 200 treadwear rating rule, if that's a priority.

[Jackal]

I'm ruling out the RE-71R as it isn't available in the 225 width.  I have a set of super light 15x8's and I'd like to maximize the width of the wheel with a wide tire.

Several of the tires on your list are "R-compound lite" tires designed for dual street/track use: R888, RA1, NT01, and A048. They'll all need some heat to work best, plus none of them conform to the 200 treadwear rating rule, if that's a priority.

I believe in SSP I can run the R-lite tires can't I? I have a bit of reading to do on the prepared classes.  I don't like being placed in them, but by the letter of the law,  I think that's my placement.

I've been using this link with the 2018 rules and Lotus class moves.

http://www.asncanada.com/…/2018-Autoslalom-Appendix-A-SCCA-…

SS    = Elise SC (2008-11)
AS    = Elise (non-SC) (2005-11)
SSR  = Elise (non-SC) (2005-11) (see AppendixF)
SSP  = Elise, Exige, & Exige S (2005-11)
SSM  = Excluded • Lotus (all except Elise, Exige, & Esprit)
FP     = Elise & Exige (normally-aspirated) (1996-2010)

[Reijo]

Correct me if I'm wrong:   Isn't your Elise a year that was not available in North America or some such thing?  If so, you are into the SSP (Super - Street Prepared).

In Street Prepared classes, R-compounds are allowed.

If your car is legal in stock (SS) class, then you can also run SSR - e.g. SS-R cmpd class but you are allowed to run R-compounds.  Lots of 15" sizes in R-compounds.

The best R's are the Hoosier A's .... autocross compound .... not the "R" - or road race compound which will not get up to heat in autox.

[Jackal]

Correct me if I'm wrong:   Isn't your Elise a year that was not available in North America or some such thing?  If so, you are into the SSP (Super - Street Prepared).

Nope.  If there is an Elise S2 on the road in Canada,  it was sold here (with one shady exception still currently for sale out east). One thing I found is that Lotus is super at keeping track of every car they made, and mine is no exception.  The Factory was kind enough to send me the birth certificate for her showing the shipping date to Canada.

The class issue is just that it has a factory supercharger on it.  As I understand the story (and I'm still digging), it was shipped here without the SC,  and one was shipped from the factory later on.  Still in 2007, the dealer installed the factory supercharger (logged on the ongoing Birth certificate as "revised engine program"), although it was not initially shipped with the SC on it. As I've dug in...  this happened a few times in 2007 with a few Elise S2's in North America. As I understand it then... It was a not a factory option in 2007, although semi commonly done way of SC'ing a 2007.

Sorry for the long winded reply to that,  but I'm finding nothing is cut and dry with these cars.

Thanks for the advice on the tires.  I'd like to stick with a tire I can legally run on the street, so I think the Hoosier A's are a no.

[Reijo]

Yes, all the S/C'd cars are in SSP ... not stock legal.

Jay, of course, has his 2007 Exige S (with the supercharger) that we ran in ASP some years ago (2009-2010  I ran with him).  They later moved the car from ASP to SSP as they tend to do in the SCCA with classing shuffles every year. 

In SSP you could install a supercharger from the Exige in an Elise as others have done.

And speaking of which, I dropped in at the Badlands office with Rick B. a few days ago and saw Jay's Exige.  His motor from Australia has come in - after waiting 4 years!  Looks good!   A V-6 with something over 450 hp (not s/c) ... It will be a SSM car and will scoot!   

[PedalFaster]

It wouldn't surprise me if the Rival S 1.5 and the Nexen were as fast or faster than the semi-R-compounds on your list for autocross. It's just one test on one day, but check out this comparison between the R888R, the Rival S 1.5, and the Hankook RS4 by multi-time national champions David and Kim Whitener: http://www.tracktuned.com/feed/2017/3/19/tire-test-toyo-r888r-and-hankook-rs4.

I swear I recently saw another test somewhere (GRM?) with a similar setup (autocross tire vs. semi-R on an autocross course) with a similar result -- semi-R definitely better on a road course, but around the same on an autocross -- but I can't find it.

[Rathburn]

The new Direzza ZIII not worthwhile?

[PedalFaster]

I don't know anyone who's tried the new Z3, but GRM (David Whitener again) did a comparison test between it, the Rival 1.5 S, and the RE-71R and found it to be comparable: https://grassrootsmotorsports.com/articles/summer-tire-test-bfg-rival-vs-bridgestone-re-71r-v.

[k1l4m]

I would still consider the RE-71R; a 205/50/15 works well on a 15x8 and will give crisper responsiveness. Doesn't last that long but at ~$500 it is a bargain.

For a street/autox 225, Rival S 1.5 will be slightly faster than the RS-4. RS-4's are still good and last a long time.

I guess you need to decide what is most important: street or auto-x performance, responsiveness or max width, price, longevity? If maximum width is a priority, you could see if a 245/40/15 may fit? Although I don't think that would work very well on a 15x8.

[Shifting gears]

I ran R1R’s on my miata this year, they weren’t too bad

[John in Calgary]

Not sure if its obvious yet, but all these sizes are first and second gen Miata sizes, so a good spot to start is looking at what the miata guys were running down at any of the nationals.

A quick look on Tire Rack shows that the Z3 and the RE-71s only go up to 205s in 15" sizes while the Rival S 1.5s are available in 205, 225 and 245 sizes.

My experience (rookie level driver, first time on 200TW tires) with the Rivals on a light car (my '92 Miata) is that they are definitely difficult to keep up to temperature on cool days in Calgary - during the second day of the Fat Kat challenge (temps were quite cool), the only time I could get them up to temp was right at the end when I wasn't spending any time waiting between runs, then they just got better and better (I was breaking out each run!).  That said, I think they fit my driving style better than the RE-71s - the RE-71s seem to like a more precise driving style, while I get away with a lot of loose and sloppy with the Rivals - they just don't fit the Calgary temp variability as well.

John