What wheels do I need?

[Mark Tearney]

3 minutes ago, jonjh1964 said:

I fitted 13" x 7" ET20s to mine having had Team Dynamics 15" x 7 ET23 on it before - need to adjust the top shims on the cycle wing mounts by 1 x thick washer.

with 205/60R13 R888Rs

They look great they really suit the car.

[Steve20]

Talk to David at https://www.randr-alloys.co.uk

 

I recently bought a set of CXRs, great service and advice.

 

Good luck!

 

Steve

[TLF]

Evening. 

Resurrecting an old thread again, I too am looking to get a second set of wheels / tyres specifically for Track use. I've just taken ownership of a 19 plate SEiW FW with 15" Team Dynamic rims fitted with 205 x 50 TOYO Proxes R1R's. and am thinking of getting a set of 13" fitted with what still seems to be the "Go To" R888r's.... I appreciate the theoretical benefits of the smaller wheels, better acceleration, less gyroscopic resistance etc, but am a) wondering if the road / track swapping from 15 to 13 will need very specific and differing geometry set ups (appreciate the effect on recorded speed, but "think" i may be able to have differing screen set ups / calibration through the Digidash to compensate)  and b) If i'm better going for full slicks for track or am i asking for problems with the additional grip from both a structural strain and engine / oil point of view.... ?  (2.0 Duratec)... have a friend who developed frame issues / failures, who suspects running full slicks on an MK was partially if not wholly to blame... ?

Apologies if this is a tedious perennial subject for you seasoned chaps, but as a newbie would appreciate knowing what the current thinking is and any advise / pitfalls to look out for. 

[Jenko]

I think you've pretty much hit the nail on the head...Reality is 15's look good, but much like the current trend in all cars, the bigger wheels are usually at the cost of the general ride. 

 

Quite honestly 13's are much more suited to a Westfield. The main advantage being improved steering feel, and the positive affect they have on reduced unsprung weight. You can also look at sizes, a duratec  car such as yours will be relatively light, so consider going thinner at the front. I would bet good money (as this is exactly what I did on my previous Westfield) that the difference between 205 / 50 / 15's all round to 185 / 60 / 13 front and 205 / 60 / 13 rear would be considerable...possibly one of the most noticeable mods you could make.

 

The suspension my indeed need tweaking, but the circumference actually doesn't change too much as the R888's have a higher profile. but possibly just a slight reduction in the shock clicks and a look at the ride height is all thats required. In a perfect world you would of course benefit from a full suspension set up.

 

Full slicks does start to require the need for dry sumps - in fact even with R888's it could be worth looking at a baffled sump (Someone duratec savvy may want to comment on this). 

 

The swapping between wheels is a nice idea but again, if I was a betting man, I would put good money on you going to 13's and never going back.....

 

 

 

[Andrzej]

@TLF  - re : slicks on Westfield . I drive only on slicks, if fact never had a chance to drive it on normal tyres. But - what Your friend sayst regarding strain on chasis is true in my opinion and experience  (below picture)  - front lower wishbone bracket on straight flat track in turn. I supouse due to fatique and not solid construction of this element . I am convicted that this can not happen on road tyres.

 

On slicks g force approx 1,4g is no problem without aero to achieve, on road tyres / semislicks is hard to achive 1,0 - 1,1 (not semi it is rather 0,8-0,9) . 

Saing that, if You want to achive proper laptimes ,there is no chance to be close on normal tyres to slick results. 

Additionaly 13" slicks are very cheap (used after formula : Michelin S412 and Pirelli DM 540/200 front and 240/580 rear) 

As for the geometry ,I would say that not the tyre/wheel size change but application is what requires different geometry. I mean - on track You need much different geometry than for road. If You stay with road geometry and use best slick tyres there will be no results.  Opposite - track geometry I would not use on road. 

So - if You want results and best possible lap times - 13" and slick . And reinforcement of some chasis points. 

If driving track for fun, not focused on results - road tyres, still good to have 2nd set for track and other for road . If there is some class that requires road tyres - there is a chance for results too - using best possible semislick and test many geometry settings. 

As for the oil - I use raceline sump on zetec, no problems with oil pressure or level at all. So no worry if good wet sump installed. 

 

)

 

[S2T]

58 minutes ago, Andrzej said:

 

 

On slicks g force approx 1,4g is no problem without aero to achieve, on road tyres / semislicks is hard to achive 1,0 - 1,1 (not semi it is rather 0,8-0,9) . 

 

 

 

 

With due respect I would disagree with your assertion about lateral g on road tyres. Just quickly looking back at my data I regularly pull lateral g of 1.4 - 1.6g using semi slick AR1 tyres, that said a lot of time has been spent getting the mechanical grip to my liking. In fact looking further back when a proper race driver drove my car on 888s he pulled 1.68g

[Dave Eastwood (Gadgetman) - Club Chairman]

I have data logs of the old XE powered car regularly achieving 1.2 - 1.4g on Toyo R888's, (on track) too. And I'm sure with a better driver, that could have been improved on!

 

(I've also got data logs of quiet early morning runs easily pulling 1.2-1.2g with the R888 on the tight twists and turns of the Cat and Fiddle road, pre the reduced speed limit.)

[Dave Eastwood (Gadgetman) - Club Chairman]

I'm not sure how true it is, but I've heard quite a few track day goers, who have experienced brand new slicks on their Westfields, as well as second hand, ex-race series slicks, all make a similar comment: The brand new slicks, can have significantly more grip than the semi-slick, track day style tyres, however, the heat cycled second hand slicks usually don't get near that, and are often similar to/only slightly better than a new set of semi-slicks. HOWEVER, for regular track day use, the second hand slicks were much, much cheaper than brand new sets of semi-slick track day tyres. SO it worked out much better for the frequent track-dayers, to use the full slicks.

[S2T]

26 minutes ago, Dave Eastwood (Gadgetman) - Club Secretary said:

 

 

(I've also got data logs of quiet early morning runs easily pulling 1.2-1.2g with the R888 on the tight twists and turns of the Cat and Fiddle road, pre the reduced speed limit.)

Having accompanied you back in the day on some of the Cheshire Group jaunts I am not at all surprised...lol

[Andrzej]

Hmm if You say that must be true (about such high g on road tyres, I had experience on road and slick on other than Westfield car hence those values)  , I assume with proper geometry , and tyres like AR1 which are quite "solid". 

Also there is a issue with measuring tools, but assume those who are measuring g dont use smartphone gps but better instruments. 

 

As for the heat cycles, yes, I have noticed that change of grip with more cycles in fact. There must be even more drop of grip if one use bran new slicks.  But does this not affect almost-sloid semicliscks in soft compounds ?

Set of used still nice slicks for Westfield costs approc 100-120GBP , last seasson I have made approx 1000km on approx 10 trackdays , used 1,5 of a set of tyres. Not sure if good semislicks would cost sililar. Also there is a weight issue, those Pirellis are really lightweigt, Michelins not as much, but I suppouse still lighter than road tyres. 

[Dave Eastwood (Gadgetman) - Club Chairman]

Measurements taken and logged via calibrated Race Technology DL1 motorsports data logger, with internal accelerometers for g and external GPS sensor etc.

 

So no, not a phone.

[Andrzej]

Found some graphs with semi, in fact those sometimes touches the 1,4g limit, but its just sharp peak, would not consider this as constatnt possible grip, also dont know if exact corner is flat or angled. But assuming proper really geometry shows that possible. 

 

www.tyrereviews.com/Article/Road-VS-Trackday-Tyres-Data.htm

 

 

 

[Ian Kinder (Bagpuss) - Joint Peak District AO]

3 hours ago, Andrzej said:

Found some graphs with semi, in fact those sometimes touches the 1,4g limit, but its just sharp peak, would not consider this as constatnt possible grip, also dont know if exact corner is flat or angled. But assuming proper really geometry shows that possible. 

 

www.tyrereviews.com/Article/Road-VS-Trackday-Tyres-Data.htm

 

 

 

T1R - nooooo. They're not good on a light kit car!

[Pco]

8 minutes ago, Ian Kinder (Bagpuss) - Joint Peak District AO said:

T1R - nooooo. They're not good on a light kit car!

Tr1s I’ve got a set with 6mm about to come off my car. Also got a video recording 4.8g with tr1s 🤣

[Andrzej]

Well, dont know t1r, we dont know the conditions when testet, how they heat up tyres etc. Everything can be heated enough (well almost   ) , I was driving once (1100kg car) on approx 15years old (!) ,but stored properly in dry, dark conditions, slicks which was when new already in Hard compound , imagine those after 15 years ! but hot day, few (4-5-6) heating laps with a lot of braking to heat rims and inside of rubber and even rear (this was fwd with light rear) was sticking quite ok. In fact no worse, I would said better (was not recorded g those days) than semi I that season also tested - Nankang ns2R in soft ( TW 120) compound.