racing dunlops to fit standad sprint wheels ?

[andyj007]

Hi All, what if any racing dunlops Cr range will fit the standard sprint wheels ... fancy using some on a track day .. i do have TTR narrow rear shocks ? also there always som egoing cheap at teh historc races with 1 session only.. thanks
Aj

[StressCraxx]

This will provide some info on sizes. The section width is an issue with the S3 and earlier, but you may be ok with S4 wings.

https://www.longstonetyres.co.uk/vintag ... lop-racing
https://www.longstonetyres.co.uk/vintag ... cr6zz.html

[661]

I'm not sure they'd fit the arches. Even the 4.5 L section 'wets'.

[vstibbard]

I’ve used CR450M in s1 elan, took some fiddling to find the correct offset to allow 5” rims to fit.
I suspect CR450L which was OEM s1 26R fitment would be easier as it has less bag in the sidewalls.
I love driving classics on cross ply race tyres, 4 wheel drifting with ease. I had a memorable race with friend in S4 Elan and I was driving an Alfa 105 GTV coupe, at the end of the race the flag Marshalls were giving us a huge cheer, having enjoyed the entertainment.
I hope you work it out.
Vaughan

[andyj007]

thanks the dunlop states 450L13 Dunlop Racing CR65 tubeless, crossply tyre is an L-section tyre, and is suitable for use on wheels with a width of 3.5 to 7 inches, with an overall diameter of 560mm, a section width of 167mm and a tread width of 115mm.


stock 155 80 13 gives us ..579d x 155mm x 124mm sidewall depth
CR 65 450L13 gives us 560 daimeter x 167mm

im not getting accurate information as it seems i dont have all teh info i need to input ,, i will have to get a used race tyre and mount it to see i suppose ..
ive still got standard rims , although revolution have the following in stock 5.0 x 13 4 Spoke which i need to check what offset they are running..

thoughts ?

[andyj007]

so further information that i have worked out
looks like the Dunlop rafcing cr 450 x 13 tyres at their widest at 7mm wider inside and 7mm wider out side
the dunlops sit 14mm lower at the centre top and 7mm less each side at centre left and right.. when both sat on a surface
Therefore providing i have 7mm of clearance or more from my standard tyre to my new narrow platform springs , & 7mm from my standard tyre to to my rear arches we are onto a winner .... i think !


the original tyres
155 x 13
BRAND Pirelli
EAN 8019227432176
TYPE Radial
ACTUAL WIDTH 153mm / 6.02"
OVERALL DIAMETER INFLATED 574mm / 22.60"
RIM DIAMETER 13" / 330.2mm
TREAD WIDTH N/A
ROLLING CIRCUMFERENCE N/A
WEIGHT OF TYRE 6.4 Kgs
LOAD INDEX 78 = 425 kgs
SPEED RATING H = 130 mph / 210 km/h
RECOMMENDED TUBES Michelin 13D13
TUBE OR TUBELESS TL (Tubeless)
RECOMMENDED RIM WIDTH 4.0" 4.5" 5.0" 5.5"

Dunlop cr 450 x 13 BRAND Dunlop Racing
TYPE Crossply Racing - L Section
ACTUAL WIDTH 167 mm / 6.57"
OVERALL DIAMETER INFLATED 560 mm / 22.0"
RIM DIAMETER 13" / 330.2 mm
TREAD WIDTH 115 mm / 4.52"
ROLLING CIRCUMFERENCE N/A
WEIGHT OF TYRE 5.7 Kgs
LOAD INDEX N/A
SPEED RATING N/A
RECOMMENDED TUBES 13D V13 Michelin
TUBE OR TUBELESS TL (Tubeless)
RECOMMENDED RIM WIDTH 3.5" - 7.0"

[vstibbard]

Be careful, the critical measurement i discovered in my journey for S1 was the bag in sidewalls was widest point when fitted to rims, the tread is narrower! Note I was fitting M series which are lower overall profile and slightly wider sidewall bag.
I tried two sets of 5” rims for different manufacturers with minor variations in offset before having a third set machined with special offset, I also fitted 26R rear wishbones to allow rim to have less offset.
Finally, it also required replacement of TTR supplied springs as the adjustable platforms setting was very close to the sidewalls widest point and under certain points rubbed the sidewalls. Solution, a custom set of small diameter rear springs which lowered the adjustable platforms.
A friend racing in Group S in Australia did fit M series to s4 race car with small adjustable spring platforms, he used +2 alloy rims on his car.
Expensive exercise but worthwhile as my car raced in Australia from new, the car was great fun to drive and personally looked terrific.
Any one after Compomotive 13x5” minilight wheels, I’ve a few sets!
Vaughan

[andyj007]

thanks Vaughan , interesting.. i have the ttr narrow spring , ive measure up from my existing 1980 gt80 tyres adding the 7mm will touch the arch but only just , but may clear when on ground its ramp at mo..
some wheels with some offset to sllow another 10mm inward would be perfect.. i guess im just going to have t source a used race tyre when the season starts mount it and see..

[vstibbard]

I called the Aussie Dunlop race tyre supplier and they leant me one!!
I relived my arches and glassed small diameter cord to retain stiffness.
Cheers V

[andyj007]

have you picture of arch and wheel ? end on

[vstibbard]

Drop me your email on PM and I’ll share a few pictures.
Cheers
V

[dougal cawley]

Hi

i just thought i might give a heads up, that although Dunlop Racing are very cool tyres and great to race on they are not road legal in 13"

[andyj007]

yes i am aware of that ..
was more for light track day work and the look.. would be better than teh 40 year old GT80 goodyears currenty fiited

[tonyabacus]

Dougal may know better but it used to be illegal to use racing tyres on the road, which if still valid means you may need to carry the Dunlops whilst using road tyres to get you to the track or use a trailer
Tony