[robbo mcs]

Quote: Originally Posted by tm75tm

Guys - I am getting quite abit out of this so keep the banter going. I have spent the last few days at the various tyre/wheel resellers and am now more than confused as to which tyre to head for (in a semi slick variant) and am even considering a 15" package for those track or twisty mountain days? Thoughts?

Hi,

A few thoughts to help you out.

Generally, with a wheel and tyre package you want to go for the lightest package possible. A lighter wheel means less mass to rotate. Also, it means the suspension works more effectively, as the springs are better able to keep the wheels in contact with the road.

Generally, smaller wheels are lighter. This is especially true in the mini where the 17" wheels are very heavy.

However the trade-off for going smaller is a smaller contact patch. With standard wheels the 15" is a 5.5" rim that fits 175's vs the 16" / 6.5/ 195 and 17" / 7/ 205. Personally I feel the 5.5" rim would be a little narrow for serious track work.

The other consideration is brakes. If you are ever considering a big brake kit you need 17's to fit over it (and obviously need 17's for your street rims too). However, personally I wouldn't worry about the brakes, the standard ones are pretty good.

I use the standard BMW 16 lights, and they work fine.

However, probably the best option is to go aftermarket, where you can get much lighter rims. For instance Boo's 17" Chronos weigh less than my 16 minis.

As far as track tyres go, you should be looking for a R compound tyre. These are commonly called "semi-slicks" which is a misnomer. These tyres have a softier, grippier compound, ideal for the track. They have a rudimentary tread pattern, and work suprisingly well in the wet. They are street legal, but generally are only suitable for short drives as they are very noisy, wear quickly, and can be slippy on a wet greasy public road.

On the track these tyres give much better grip, and more feedback, and will improve your times dramatically.

Do not buy true slicks! These are really for hard core racing, and it would is more sensible to progress from street tyres to type R.

The only type R's I have seen people running on the mini are Dunlops and Yokohamas, and both seem fine. I have seen other brands on other cars, such as Hoosiers and Michelin pilot sport cup (both expensive and very soft) and Kumhos (not rated well).

Some people might try and push you towards Falkens. They have a tyre (Azenis?) which is basically half way between a street tyre and a type R tyre. Some people in the BMW club have these. It is a good compromise if you only have one set of rims. However, from what people say it is a major compromise both on the road and the track.

I run the Dunlop formula R DO-1J 205/50/16. These come in 2 compounds. You should get the harder compound as they last better, but still perform well. Boo runs the yokohamas and they seem fine as well. A set of Dunlops is $1350. The standard tyre shops often have no idea about type R tyres. If you look in one of the motor mags (eg auto action) there are usually ads for tyre shops selling these tyres.

If you are running stock suspension the outside of the tyres will wear very quickly. To keep the wear even you need to get the tyres flipped on the rims every couple of track sessions, ie get the tyre shop to turn the tyres around so that the worn outside becomes the inside. If you do this carefully, and rotate the tyres front to back you should be able to get 10-12 track sessions, depending how hard you drive and how long the sessions are.

By the way, I fit all my tyres in the back of the car with the rear seats down. Therefore I generally drive to the track on street tyres and change them over there.

Attached is a picture of the dunlops, with a worn and new tyre.

Robbo

[Darryl]

Just to add to Robbos post - I also don't think the Mini "needs" a brake upgrade, but if you want one go for it. A pad upgrade is all you'll need for track days/supersprints.

If you can get 15" rims that are really light get them ie: quoted weights on Lenso maglites 15x7 - 4.9kg, 16x7 - 5.6kg (I'm unsure if these are available for mini fitment but are a guide) as this is all unsprung weight its REALLY good weight to lose (do a search for this for an explanation).

With tires you may well have to suss out the local race tyre distributer s, the local Bob Jane may not stock R spec rubber - to help with choice read the Uniform Tire Quality Grading explanation (see below) you can use this to get some sort of rough comparison between brands. Toyo do a really good tyre thats cheap (Proxy RA1's) that compares very favourably to the Yoko A032R's.

If you go to a set of wheels and tyres for the track couple of rules: if you use them on the road they'll wear out REALLY quickly. When you take them off the car bag them and keep them out of the sunlight, this will stop the rubber hardening and no-one wants hard rubber.

Hope this helps!!



The Uniform Tire Quality Grading rating is a quality rating system developed by the American Department of Transportation. It is designed to tell consumers the relative performance of passenger tires.

Below is an example of a UTQG Rating: 150A B

The "150" indicates the treadwear rating
the "A" indicates traction
the "B" indicates temperature

The ratings are based on controlled conditions based on a particular course. A tire graded 150 would wear 1 and a half times as well as a tire graded 100. Traction ratings are A, B, and C, from highest to lowest. This measurement indicates a tires ability to stop on wet pavement. Temperature ratings are as follows from highest to lowest: AA, A, B and C. These measurements indicate the tire's ability to sustain high temperatures which often cause tires to wear away quickly or in extreme conditions lead to sudden tire failure

[Boo]

Quote: Originally Posted by robbo mcs

I tend to agree with you regarding chasing tenths of a second. I am enjoying myself, and dont feel the need to spend more money. However, it still hurts when I think about the time Boo beat me by 4/1000ths of a second at Wakefield!

Robbo