15" Tires

Ant · #1 (**permalink**) 12-21-2003, 10:23 AM

As I am seriously considering ordering 15" Trigo wheels for my cobra, having looked at Roger Kraus racing Cobra tires , he appears to supply a good range of 15" tires! A lot of racers appear to be using 17" tires, probably for the extra room for bigger brakes and also the lower tire profiles. Do the Goodyear/ Hoosier 15" road and race tires provide comparable grip to a 17" equivalent tire?

http://rogerkrausracing.com/cobra.html

SCOBRAC · #2 (**permalink**) 12-21-2003, 07:35 PM

most of us who run 17's do so for the V or Z rating, limited sidewall flex and improved compounds. The 15" tires avaliable are pretty limited and tend to be greasy at best. Roger Krause is an excellent source for non highway approved tires which may or may not be legal or practical in New Zeland. Most of the tires you see on his sight will not comply with highway use regulations here in the US.

No 15" tire will grip like a 17". That is just a simple truth of physics and a law of nature The aspect ration of a 35 series tire has 15% less sidewall than a 50 series. I was able to go from a 295/50 to a 315/35 by switching to 17's. No 15" tire I am aware of presently is rated above an S rating for 112 mph. Which to be honest is faster than 95% of all cars will ever go.

Good Luck

clayfoushee · #3 (**permalink**) 12-21-2003, 07:56 PM

My experience is completely consistent with what SCOBRAC said above. I have both a 15" and 17" Y-rated set of wheels and tires. I've driven the car extensively on both. There is simply NO comparison in the handling and performance with the 17s on the car. I prefer the 15" "period-correct" look (why I keep them), but it depends upon what you want the car to do and how hard you push it.

Okiesnake · #4 (**permalink**) 12-21-2003, 08:37 PM

Does any manufacturer make a 17" 5 pin drive rim?

SCOBRAC · #5 (**permalink**) 12-21-2003, 08:51 PM

I should have mentioned I too tried the Trigo's. I really wanted the "correct" look. I bought a new set, mounted tires and guess what? Despite promises that they would from trigo's owner, they did not fit my car. the offset was too great. That was partly my fault, but he seemed convinced they would fit. The owner of Trigo suggested I trim my fender wells to get them to fit.

I sold them on e-bay for a $500 loss. At least they went to a fellow club member. Phil Schmidt owner of PS Engineering (PSE) will craft a 17" wheel to your specifications or tell him what you want and he will do the calculations for you. He offers wheels in widths from 9-14" in width and in any offset / backspacing you like.

Search PSE here in the club for his address. I have photo's of the 9x17 and 11x17's in my gallery. They fit like a glove and are pretty faithful to the Halibrand style.

Ant · #6 (**permalink**) 12-21-2003, 09:05 PM

SCOBRAC, CLAY

What I am considering is having two sets of Trigos and having slicks on one set and cruising tires on the other, this keeps the original look!
Curious about offset quoted as 3.5" by Trigo is this inwards or outwards?

In New Zealand MANZ (Motorsport New Zealand) the classic historic, replicas etc have tightened up on regulations to keep it more down to earth, and they frowned when I asked them if I could run 16" wheels.

I had 17" knockons (Arrow wheels NZ) which had the threaded hub and correct alloy lug nut on a Cobra, they were great, never came loose, but 10 years ago the tire selection was dismal I had to run tires designed for a Ferrari road car at NZ$1250 each, no grip with 600+hp - I was still going sideways half way down the main straight if I was agressive!

Maybe I should just say stuff it and get some PSE 17" Knock ons, I assume that PSE make a Knock on and can supply hubs lug nuts etc?

clayfoushee · #7 (**permalink**) 12-22-2003, 07:13 AM

Ant,

I have no experience with Trigos or PSE's. I run Compomotives (lug nuts and fake spinner), which are Halibrand replicas.