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Fred Boothby
United Kingdom
365 Posts |
 Posted - 07/06/2022 : 13:26:32
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| Many, many years ago if you wanted to go motor racing you had no choice of tyres. You bought a set of Dunlops, for that was all that was available. Dunlop Racing tyres were available in two compounds, the standard 204 and the hard 184 for long distance racing. Then a 'super sticky' compound was introduced, the 484, and if you were a serious racer you had to have a set of these or you were nowhere. About this time classic/historic racing was developing and the rules and regulations about wheel sizes were not as strict as they are today , so it was quite in order to buy a set of 16" wheels and a set of Dunlop R7s tyres with 484 compound and go racing. Now our old cars, when driven to extremes, are designed to slide rather than grip, and I remember a distressing incident at Brands Hatch when the intended slide turned into a grip and a roll and the subsequent fatal accident inquest put down the tyre choice as a contributing factor. Subsequently some race organizers banned the use of these 'super sticky' compounds, insisting that 204 was the hardest permissable, and scrutineers would highlight the compound marking on each tyre and this was also checked on the starting grid. For our MMM cars until recently we did not have much choice especially in the 4.00 x 18" size. It was Avon SMs only. Recently more tyre manufacturers have been producing rubber in the sizes we need. Blockley springs to mind, but I know there are others. Speaking to fellow competitors in various circuit paddocks I have heard " Mr X has fitted a set of those super grippy tyres which is why he is so quick". Now I am certainly not advocating a ban on Mr X or his 'super grippy' tyres, just attempting to start a discussion about this matter, for I am very concerned. I have no evidence, other than my own eyes, to say that the most unfortunate accident involving one of our number at the VSCC Race Meeting at Donington Park was caused by this choice of tyres. I am just suggesting that anyone intending to fit a new set of something and then compete should think long and hard about their choice of tyre. |
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George Eagle
United Kingdom
3244 Posts |
Posted - 07/06/2022 : 15:12:21
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Good advice. I recall Collin Tieche overturned his very rapid J4 when it was fitted with racing tyres - they could have been 16 inch?
George |
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Dolts
United Kingdom
1129 Posts |
Posted - 07/06/2022 : 16:03:23
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Certainly an interesting one Fred, there are a lot of claims and performance gains from certain new types of rubber for sure.
I personally am a fan of blockleys both the 19 450s on CLX and now my 18 450/500s on the Ripple. Why ...because they don't grip too much! I m much happier with the slide rather than a snappy grip. Makes me drive slower in and hopefully quicker out!
Having said that I m amazed any tyre gripped in those conditions on Sun!
Mark Dolton
Triple-M Racing
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Onno
Netherlands
1054 Posts |
Posted - 07/06/2022 : 16:32:07
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+1 for the blockley slide.
We could lobby the VSCC, MGCC and other relevant organizations though some might be sponsored by the tyre supplier of Mr X......
Onno "J,D,M" Könemann |
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Dolts
United Kingdom
1129 Posts |
Posted - 07/06/2022 : 16:59:57
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like us!!!
Mark Dolton
Triple-M Racing
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Christian H
Germany
58 Posts |
Posted - 07/06/2022 : 20:13:50
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George, they were 16 inch with 5.50´s - over-efficient for our cars...-;)
Christian Hoeptner |
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Foz
United Kingdom
773 Posts |
Posted - 08/06/2022 : 11:18:05
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Used 400 x 19 Blockleys at Donington....... could see the tread perfectly going into the chicane as both front wheels locked up! Accelerating as they aquaplaned....... so some very strange lines through the corner. Knowing that they are not gripping is better than the unexpected......
Going off the black stuff onto soft grass or kitty litter .... ok if more or less straight line or with no lock on the front wheels means you go quite a long way but stay upright (Been there/done that).
Sideways or with lock on can cause the car to roll ( also done that !)..... Sometimes it is down to good/bad luck. Our "period" narrow section tyres are part of the issue when sliding sideways. I had a spin exiting Old Hairpin but had time to get the front straight before running onto the grass..... the very wet trip home washed the evidence away.
I do not think any of the currently available 18 and 19" tyres suitable for our cars are a problem in the dry. QA0255 was on the 500 x 18" Blockley .. super grip dry and ok in the wet ... never felt unsafe as a result of the tyres. Tried them on the Rat......did not feel right on the smaller car and had to brake earlier to overcome the increased effects of the larger/heavier unsprung rotating mass.
Part of the pleasure(?) of racing Triple-M cars is their limitations....... long may it continue.
FOZ |
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Richard Hardy
United Kingdom
2165 Posts |
Posted - 09/06/2022 : 13:42:19
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Nobody as yet has mentioned incorrect tyre pressure settings which can of course be a contributory factor and relevant to the topic.
I remember Peter Plaskitt's Brooklands PB had its fair share of two wheeled cornering before its last race at his hands around 10 years ago where it barrel rolled several times. He was running on 4.50 19 Blockleys but at incorrect tyre pressures i.e. too low.
Rich
Vintage MG Parts |
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Fred Boothby
United Kingdom
365 Posts |
Posted - 09/06/2022 : 16:27:52
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| The tyre pressures on the car that rolled at Donington were correct. Normally set at 38/40 for dry warm conditions, they were reduced to 34 psi all round for the wet conditions. On my J2 for that race I was running 34 front and 36 rear. I think tyre pressures can be ruled out for this incident. |
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Foz
United Kingdom
773 Posts |
Posted - 12/06/2022 : 11:31:01
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I do not think "plastic" Peter's incident was due to wrong tyre pressures. It is probably my fault or the enthusiasm of the moment, track conditions and the "Tricksey" spec. of the P-type.
Peter was on holiday in Porto the same weekend as the Historic race meeting and we shared the same accommodation (only time I have stayed in a Hilton!) and I gave him one of my tickets so he spent the weekend in the paddock/pits/track and saw what we did and that made him decide to join in and buy the P-type. That weekend had monsoon rains one day and 35*+ sun the next so he saw and had explained the water/oil/fuel/tyre check made before each race.
When he purchased the P-type he was mentored by several Triple-M racers and Mark Boldry went with him several times so he would know what to do. That P-type has several modifications ... some of which will alter the handling... I know the VSCC were not happy with the car. A combination of any/all/none of the above plus the "Luck of the Game" ........
There are several pictures of the RAT on less than the usual number of wheels... trying to race under ACU rules! Even with 400 x 19 at 38/40 psi the tyres work hard!
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Edited by - Foz on 12/06/2022 11:34:13 |
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Tim Sharp
United Kingdom
304 Posts |
Posted - 12/06/2022 : 15:32:06
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Guys
Wow, what an interesting thread.
If I was not Hors de Combat due to surgery & chemo I would have been out racing earlier this year and without knowledge of what has been discussed in this thread may well have been running with pressures well below those recommended by the more experienced and potentialy putting myself at risk. I have learnt quite a lot from this and will remember it for next season when I should be allowed back.
Be careful out there and enjoy the rest of the season.
Regards
Tim
Tim Sharp
PB0685 - Nuneaton |
Edited by - Tim Sharp on 12/06/2022 15:50:37 |
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andrewmorland
United Kingdom
18 Posts |
Posted - 12/06/2022 : 17:59:28
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| TYRES:- I have to agree with the more experienced and competent racers than myself that tyres not gripping too much is better than unexpected and sudden grip! The Avons and especially the Blockleys give plenty of warning and are progressive in their adhesion in the wet and the dry. Initially I was envious of the grip that some cars with the latest tyres that I have followed are taking tighter lines while I have to use all the road. However after a triple spin with the L1 at Cadwell on a patch of oil at 65mph plus I am sure that if I had the new super grippy tyres the car would have turned over on the first rotation! |
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Tim Sharp
United Kingdom
304 Posts |
Posted - 14/08/2022 : 14:48:15
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Fred
Referring to your posting of 9 June, are these pressures "cold" or "hot".
If "cold" what would be a sensible increase to factor in if checking pressures "hot"?
We are hoping to go to James Baxter's VSCC Track Day at Blyton on the 14th September https://www.vscc.co.uk/page/forum?cgID=2&cID=2&tID=17376 and one of the things I want to play with that day will be tyre pressures hence the question of the "cold" v "hot" increase to factor.
Regards.
Tim
Tim Sharp
PB0685 - Nuneaton |
Edited by - Tim Sharp on 14/08/2022 14:48:37 |
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Fred Boothby
United Kingdom
365 Posts |
Posted - 14/08/2022 : 18:00:35
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Tim. Firstly I am using Avon SM 4.00x18 tyres. Before practice I set them to : 33 Front / 35 Rear for wet conditions. 35 front / 38 rear for dry conditions. 38 front / 40 rear for dry and hot conditions. After practice I quickly check them and obviously thay have increased by a couple of psi. I reset them to pre-practice settings.
I may be wrong using these pressures but they seem to have worked quite well on my little J2 so far , but as I have only managed to beat Foz once in ten years , maybe he has different views on the subject ! Yours Fred |
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Dolts
United Kingdom
1129 Posts |
Posted - 15/08/2022 : 19:40:53
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On CLX , 19 450s I run at 38 rear and 36 front in dry. 35 Al round wet.
As Fred says, Sometimes need to ease pressures after practice as they increase with hot weather. But still set at 38 rear.
38 at front makes car go straight on at copse in dry 
But that’s a preference to how I like the car to handle. Nice and firm, Bit more back end drift!
On the Ripple 18 450:500s I ran the
at 35, for all 6 races this year. but that was in the slippy conditions. One day I ll have fun in dry.
Mark Dolton
Triple-M Racing
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Edited by - Dolts on 15/08/2022 19:43:32 |
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Blue M
United Kingdom
1474 Posts |
Posted - 18/08/2022 : 12:07:06
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| Avon SM are quite grippy tyres with softish rubber. This is why even on motorcycles 8 to 10 thousand miles is the norm. They also have very pliable walls so perhaps they are not really suitable for racing MMM cars? |
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