Circuit Semi Slicks

[gtr jet]

Now that you mention it, maybe it's not worth the extra headaches. Probably better off getting a set of semi's.

[JimmyRickard]

What size tyres do porsche cups cars use?

[PN-Mad]

I think from memory it's 24 front 29 rear 18 inch. So for a GTR, you want the rears only

[JimmyRickard]

290x18?

[PN-Mad]

Sorry, the older cars used to use 24/64-18 front 27/68-18

Looks like the newer cars went up some sizes. 27/65-18 and 31/71-18

Used tyres aren't that hard to come by, google will show a few leads.

[Leroy Peterson]

Sorry, the older cars used to use 24/64-18 front 27/68-18

Looks like the newer cars went up some sizes. 27/65-18 and 31/71-18

Used tyres aren't that hard to come by, google will show a few leads.

as will my105.com.au

http://www.my105.com/ListingDetails/tabid/65/p/1/cid/5478/id/12962/Default.aspx

http://www.my105.com/ListingDetails/tabid/65/p/1/cid/5478/id/12958/Default.aspx

[JimmyRickard]

Was at iRace yesterday and there was a guy selling kumho slicks. The V700 were $450 a corner, for a 265/18 is pretty cheap. The Semi was only $30 cheaper. Anyone used these slicks?

[hrd-hr30]

yep, I bought a set of Kumho S700 because they were cheaper than semis at the time. Had 2 front blowouts in 3 track days, one left one right. And the third one I got to replace the first blowout, was smoking and about to let go when I had the 2nd blowout!

That was on a 180SX with unchanged front suspension setup that R888s and FZ201s, and even cheapo gemstone street tyres survived for years without any issue.

I wouldn't touch Kumhos again after that experience. And Kumho simply didn't want to know about it.

Edited June 15, 2014 by hrd-hr30

[JimmyRickard]

Yikes! Kumho really didn't want to know about it? What tyre pressures were you running?

[hrd-hr30]

32-34psi hot as recommended by the Kumho distributor. The same pressure I ran the semis at.

Edited June 16, 2014 by hrd-hr30

[Victory]

I have three sets of Kumho V70A's and I have been very impressed with them after coming from Yokohama 048's.

The Kumho's have a reputation for failures on the front if you run them too soft or with too much camber.

I had to go up about 6 pounds from the 048 hot pressures and I only run 2 degrees negative camber in the front.

It could be the fact that they have square shoulders and like to sit flat on the road but they seem to react badly to camber. The 048's have very rounded shoulders by comparison and cope with a lot more camber without any problems. The Kumho's also like higher pressures that seem more like street radial pressures than semi slick pressures.

I am happy with the performance of my Kumho semi's but you have to adjust your pressures and suspension to make them work. They are not as forgiving as other tyres on the market.

[mazman]

Weird.

I have the v70a/v700 ( arnt they the same?) in hard compound running on the supra, so a fairly heavy car. I havent had issue's with them and ive had them since start of the year, had 2 track days and 5 hill climbs so far.

I also ran them 34/32 hot for track days and even tried them at 32-30 hot on hill climbs, no issues for me.

I like them but would go mediums as the hard compounds take too long to heat up for hill climbs.

I hear very good things about the 050 yokohama's

[hrd-hr30]

Weird.

I have the v70a/v700 ( arnt they the same?)

no the V700 and V70A are different types/patterns of semi slicks. But he was asking about slicks - i assume the V700 was a typo - the Kumho slick is S700. Which are obviously a different tyre from either of the semis.

[JimmyRickard]

Sorry - it was S700 I was talking about.

[djr81]

Weird.

I have the v70a/v700 ( arnt they the same?) in hard compound running on the supra, so a fairly heavy car. I havent had issue's with them and ive had them since start of the year, had 2 track days and 5 hill climbs so far.

I also ran them 34/32 hot for track days and even tried them at 32-30 hot on hill climbs, no issues for me.

I like them but would go mediums as the hard compounds take too long to heat up for hill climbs.

I hear very good things about the 050 yokohama's

The 50's are quick but dont last very long. They also fall away in performance - not the compound - just the rubber wearing differently across the tread face. May be fixable by remounting the rhf on the lhf as they are directional. They go well from cold too.

[warps]

That's opposite of what the IPRA guys were saying when the 050's came out. Compared to the 048's, which heat cycle badly, they reckon the 050's were good till they were at the canvas, hence better value for money as you can use them till they wear out and not lose performance.

[djr81]

Well that is why I was trying to say it isnt a compound thing. Just maybe that my lardbox is a little to, umm, lardie for them.

Am sure someone will be along to tell me my set up sucks teh balls but here is a dead tyre.

Not how the tread block (for want of a better term) wears - chamfers really. Can be helped by swapping tyres side to side but the grip does fall away as the tyre ages. For me anyway.

[SimonR32]

What pressures were/are you running?

Mine chamfered as well when I first put them on, a little more camber and less tyre pressure seemed to help a fair bit.

How do you rate them against the V70A for wear and grip?

[djr81]

What pressures were/are you running?

Mine chamfered as well when I first put them on, a little more camber and less tyre pressure seemed to help a fair bit.

How do you rate them against the V70A for wear and grip?

1. Pressures were 30# which is what the bloke from Yokohama said.

2. Camber is enough I think - anymore I would have to wheel align it for other circuits/events etc. Dont think it is that far away. Did a 64.0 something which isnt too bad for 410 horsepowers, a full interior and a talentless driver.

3. NFI never ran with the ho's.

[SimonR32]

Yeah 30 hot is spot on although I think I'm running plenty more camber than you, I'm up to around 4deg now.

Thinking about giving the Kumhos a crack next, I've got the 123S down into the 63's and the A050 a mid 61.

Have a set of Ikeya Formula front LCA's to also fit so hopefully the extra track that gives will help times a little because GTR understeer is a bitch

Edited June 20, 2014 by SimonR32