Hi guys has any one used kumho v70a tyres before would they be good for hills and sprints and track days I no they won't be as stick as avons a15 but would they do as I have a new set that came on my car thanks jon

[Edited on 26/3/15 by joni]

[Edited on 26/3/15 by joni]

used them before and i thought they where great on track very predicatable,

as good as my ao48 i would say

easily
thanks
sean

ps that was on a raw striker

The super soft compound which I think may be k21 wouldn't last too long on a circuit. They are mega soft and would be ideal in a road going class on the hills. But if in modified then a15 or a92 is the only real option

[Edited on 26/3/15 by daniel mason]

Thanks guys would they be better than toyo gg

K21 are very close in performance to A15 avon slicks on a modprod or roadgoing car if it has any semblence of suspension travel. If the cars uber stiff and light then the A15s will be noticeably better.

The A15 compound seems to have a wider heat range envelope though, they heat up as quickly as the k21s, but take longer to overheat in my experience.

The A15 is technically better in cold conditions for first two or three corners of a hillclimb, but most circuit sprints will see both tyres warm at similar rates

The A15 compound ages quicker though. Buy em at season start and use them at two events or 10 events and the start of the next season the drop off will be the same. Its highly unlikely you will ever wear the A15s out, but the performance drop off usually forces you to part with 800quid to BMTR.

the k21s age less rapidly. I beleive the A15 is a 'semi cured' rubber compound. After some heat cycles (few events) they start to cure, and time does the rest. The K21s are Kumhos F3 'wet' compound which is a normal rubber compound so is cured hence a more stable and slow performance drop off. They do wear at a fair rate though. If you are serious a newish set to keep for the wets a good idea as the wear rate is so rapid yhat the grooves become too shallow to dispel water. If you are running in a class where its allowed, then you can cut the v70s to have deeper grooves to the shoulders. As std the grooves reduce in depth to the outer edges they dont expel puddles well and aquaplane, but cutting the grooves to a uniform depth does make them good for splashing throuh puddles!

The A15s will be hugely lighetr than the v70s though. If running 13" tyres, and going width for width in comparison, expect about 1/3rd less weight per tyre for the avons. They use a race carcass, very little steel, mostly rayon and kevlar belting iirc whereas the kumhos have loads of steel in them. Even at 5psi the kumhos will hold the car up no issue!

For trackdays though k21s will be destroyed in a couple of laps and the A15s maybe only a lap more. Buy cheap s/hand circuit slicks for trackdays. May take 2 laps to come up to temp, but theyll run all day and usually only cost 20quid a pop!

Kumho mediums might be ok if you cars uber light, 350-400kg for trackdays, but would be hards ideally. They wont be as good as cheap ex circuit slicks though.

For sprints and hills the toyos are average at best, ao48s little better. I used toyo SGs and the grip wasnt a patch on kumho k21s, were barely warm on hills as you crossed the finish, only anglesey and castle combe spribts really allowed them to work reasonably well.

If not kumhos, look at Avon ZZRs, only real competition for the v70as

Just west out to workshop and the stamp on the tyre is k61 so noing my luck there as hard as a goats toe

Found out med compound what tyre pressure westfield car engined do you guys think iam used with toyo and bike engine for racing and would have used 17 psi cold

I run 20-22psi but on a heavier car so have less issues with getting heat into the fronts. I would say 17-19psi for sprints will be a good starting point. What sizes are you running btw?

There are some k21 v70s on ebay now which have been cut to wets, compare the tread patterns and youll see what i mean.

The k61s may be ok for trackdays if they are a bit old, should slow down the overheating

I used to be sponsored by Kumho. I have used the soft compound and medium compound V70A... I found they were softer than the compounds suggested. The C03 was my Kumho tyre of choice which was a semi-slick rally tyre... worked well and punched above its weight alittle against the Dunlop X10/12 most my competitors were running. This was all in an Evo though. Friend does well on hill climbs with the V70a

They're great until it rains! I used to race in the Kumho BMW Championship and have had my fair share of trying to race them in the wet.....they're useless!