Wheels & tyres for sprint racing

Ben MX5 · Postby **Ben MX5** » Sat May 17, 2014 11:15 pm

Hi there,

I am new to all this and would really appreciate some help.

I bought an 03 MX-5 a few weeks ago. It's got the standard 16 x 6.5 wheels fitted with 205/45 R16 Kumho KU31's in good condition.

I plan to use the car in the standard class of the MX-5 Vic Sprint championship. This means 205 maximum tyre width, 7.5" maximum rim width and no type R tyres. These tyres are allowed:

Hankook Rs 2
Kumho KU 36
Dunlop Direzza Z1 & DZ2
Toyo Proxes R1R
Yokohama AD08 & AD08R
Bridgestone ADRENALIN RE 001

I've not raced before last weekend - I managed 156.5 in the wet at Sandown, so I've got a long way to go.

Should I just run around on the tyres I've got until I learn to drive? Or is this just a good way of ruining good road tyres? Would it be better to have a second set just for sprinting?

From talking to guys at the track and reading the forums it seems that 205/50 R15 Yokohama AD08Rs on either 949 racing or enkei rpf1 rims is a popular choice.

I also found an Enkei copy here: http://www.gumtree.com.au/s-ad/marrickville/wheels-tyres-rims/ssw-peak-15x7-38-4x100-suit-4-stud-jap-cars-4x100-honda-toyota/1043640642. They're much cheaper but still lighter than the 949s. Are these a good value option? Should I be worrying about cheaper wheels breaking at speed?

What are your thoughts?

-Ben

davekmoore · Postby **davekmoore** » Sun May 18, 2014 2:05 am

Spend tyre money on seat time.

Guran · Postby **Guran** » Sun May 18, 2014 9:30 am

What he said.

Starting out with those stock wheels and KU31s is a perfect way to develop your track skills. Your car won't be as fast as the fastest guys ... but they'll be faster than you anyway because they're more experienced. After the KU31s are finished (it could take a year or so), try the next cheapest which is probably KU36. Dunlop Star Specs are the optimal tyres in these standard classes. They're better than AD08s but I believe they're also more expensive.

Talk to Rob Downes. He knows his stuff in standard MX-5s and will give great advice.

rascal · Postby **rascal** » Sun May 18, 2014 11:21 am

Guran wrote:Starting out with those stock wheels and KU31s is a perfect way to develop your track skills.

What he said..

And even though it probably didn't seem it at the time, but that Sandown day you did in the rain was the best first day you could have had. You get to find the limits of traction at a much lower speed, so when you do exceed them, you aren't going as fast and therefore is easier to keep under control.

Ben MX5 · Postby **Ben MX5** » Mon May 19, 2014 7:13 pm

Thank you all.

It sounds like great advice - a few people told me differently and I started worrying about it.

cheers
Ben

smy0003 · Postby **smy0003** » Wed May 21, 2014 5:01 pm

There's no time to think about tyres on the first time at sprints.
The only thing that enters your head on the track is 'Fffffffffff..............!!!'

Postby **beavis** » Wed May 21, 2014 9:40 pm

Get AD08R's.
Quickest road tyre you can get.

If you are in Vic, come find me and I will show you how to get around the track quick.

Ben MX5 · Postby **Ben MX5** » Fri May 23, 2014 9:33 pm

Great - Thanks. I'll keep an eye out. I've been watching your videos, so in a way you've already helped.

Unfortunately, I can't make it to Broadford (but it looks like a great little track). I'm planning on getting to Phillip island on 5 July so maybe I'll see you there?

-Ben

Regie · Postby **Regie** » Fri May 23, 2014 9:42 pm

Yep. Forget tyres. Get some bum in seat time first.

Saying that I had KU31's on my car for a track day or 2. I was surprised on how much grip they do have for a cheap tyre

Postby **beavis** » Fri May 23, 2014 10:03 pm

Ben MX5 wrote:I'm planning on getting to Phillip island on 5 July so maybe I'll see you there?

-Ben

I should be at PI.

lightyear · Postby **lightyear** » Fri May 23, 2014 10:08 pm

If you plan on pushing the car as quick as it will go, I would get a good set of tyres. And maybe skip standard NB class, and go straight for clubman or modified. Then you can actually enjoy the car. And do quick lap times. Driving a car with rolly polly suspension, and an open diff is not as much fun.

Guran · Postby **Guran** » Sat May 24, 2014 4:22 pm

lightyear wrote:Driving a car with rolly polly suspension, and an open diff is not as much fun.

Actually I've had PLENTY of fun over the last five years with exactly this set up. :lol:

lightyear · Postby **lightyear** » Sat May 24, 2014 9:49 pm

Driving anything flat out will be fun. But I prefer the better feedback, and more direct feel. And as a plus, you can be quicker. So fun and fast.

Ned Loh · Postby **Ned Loh** » Sat May 31, 2014 10:42 am

Get some decent 'track' tyres early. I thought I'd use up the road tyres my car came with first, but when I did get some 'racing type' tyres the car was different to drive and I had to re-learn much of what I thought I'd figured out.

Keep the ones you have for the road, and get a 2nd set of wheels and sticky tyres for the track???

Ben MX5 · Postby **Ben MX5** » Wed Jun 11, 2014 10:44 pm

Hi there,

Thanks everyone who's contributed.

Ned, I am inclined to agree. It seems that the key reason not to get a second set is to do with cost whereas it seems that the cost is partly spending money sooner rather than spending extra money - and I am lucky to have enough cash to cover that much as well as make it to the track as often as time permits.

I went to FFCC's driver training day at Sandown on Monday. It was a great day - nice and dry. I managed to get below 1.41 (just) and started to get a little consistency. It felt really good (but a long long way from the class record 1.35).

At one stage I had a big oversteer all the way through turn one. I thought I'd just run out of talent, but the instructor sitting next to me was confident that the road tyres (KU 31's) were overheated. We cruised for a lap then tried again and it seemed much better. Chatting away afterwards a few of the FFCC guys were strongly of the view that I should get type R tyres sooner rather than later. In their experience: on type R tyres, the car's easier to control, people have less offs and the tyres don't overheat and go off.

1. Does this match your experience?

2. If I move to, say, an AD08R (allowed in the standard class but still meant for the track) will I notice improvements along these lines?

3. If I'm going to get a second set of rims, what's the recommendation? 15 or 16? How important are weight and width? Are we talking a second or a tenth of a second? I like the look of the standard 16's + their cheaper (and presumably won't break) but the savings are partly offset by paying more for tyres.

4. And finally tyre pressures. I started out at 36psi cold. After discussing overheating etc., the instructor had me drop them to 32psi hot (which he guessed would be about 28psi cold). This seemed to be a big improvement. Compare with http://mx5vic.org.au/motorsport/sprints-general-information/general-tips/ which recommends 40 to 45 psi.

cheers
Ben