15 inch wheels - bad for handling/grip?

[MikeFromPerth]

Hi all

Anyone compared 15 inch to 17 inch wheels for feel of the car and handling?

Do you notice the difference in terms of grip, harsh ride, etc?

Mike

[750hp]

Street or track?

On the street, it comes down to aesthetics and personal preference because either option can give you all the grip you need.

[MikeFromPerth]

Street mainly (nearly 100%) is my plan. Occasional track day perhaps, but not competitively. I like the look of 15" wheels but wondered if they are noticeably "floppy" in terms of nice crisp handling. It would seem a shame to ruin the handling if indeed it does make a really noticeable difference...

[deano59]

Originally Posted by MikeFromPerth

Street mainly (nearly 100%) is my plan. Occasional track day perhaps, but not competitively. I like the look of 15" wheels but wondered if they are noticeably "floppy" in terms of nice crisp handling. It would seem a shame to ruin the handling if indeed it does make a really noticeable difference...

two sets of rims 15 for the street and 17 with advans or avons for the track dont think i would like to track with my road tyres

[KevinW]

Bigger the wheel the more frequent the puncture - if you are running big wheels on rubber bands, there isnt much give in the sidewall, and little to protect the rim from dings in the road. Maybe that's a UK issue?

[Ron61]

I ran 15 inch wheels on the roadster and they worked pretty good on the track, but it is hard to find really good tires here for 15 inch wheels. I have 17 inch wheels on the Coupe and they seem to work quite a bit better in hard driving and cornering. And it is much easier to find good tires for them.

Ron

[Dimis]

There's limited options in 15inch.
17 certainly give more options and therefore greater potential for better tyres, and thus better handling.

That all said, I still went for 15s on mine.... I Just prefer the old school "fill-the-wheel-arch-with-rubber-not-rim" look for a cobra. But that's just me.

[*13*]

Traction is mostly covered, above. Looks aside, There is a noticeable difference in ride quality between the two. My 15" feel nice & plush. Good tires are the key to the level of traction attached to any size. My 17" grip nicely but transmit every crack in the road into my @$$.
If I had to rely on one set, it'd be the 15". Of course, I don't track the car. & if I did, It wouldn't be serious enough to necessitate 17" wheels. So it's situationally dependent, right? You can't make a wrong choice. DO what your gut tells ya

[mikeinatlanta]

Reasons for the 15" wheel
Lighter
Authentic look
Lower CG with low profile tires
Better leverage ratio for the brakes

Reasons for 17" wheel

Tire selection
Can fit bigger brakes
Assuming the same diameter, the lower profile reduces the effect of the tire "air spring" and its uncontrolled lack of rebound damping. The greater the ratio of unsprung to sprung weight on the car and the more flexible the chassis, the more pronounced this effect is. Lower profile rubber transmits the suspension movement more effectively into the springs and shocks, allowing better control of suspension movement and improving the effectiveness of spring and damping adjustments.

If you can find appropriate rubber and they fit over your brakes, low profile 15" would be of the biggest benefit to a street car that normally runs taller rubber. Problem is, you won't find appropriate rubber.

[Pman1961]

I run the 15" AVON's with a 600+ hp motor. Great grip straight and cornering with a good ride. Not as smooth as the Yokohama Avids that came with the car but all those tires would do is spin. Reason for the slightly stiffer ride is I run a few more pounds of air in the fronts so the steering is not as heavy. Guess the softer compound is the reason for that heavier feel. My Buddy has 17's and they are rough on poor roads. Couldn't imagine 18's!! My preference for looks is the 15's and AVON tires will be all I ever use on my car....

[Jim Vander Wal]

I started with 15s, Yokohama Avid S/T. 255/60 & 295/50. These were decent tires but went out of production. Comfortable ride. Better than many of the other 15 options.

Switched to 17s. 275/40 and 315/35 or 335/35. I've run Goodyear GS-D3, Sumitomo HTR Z, Michelin Pilot Sport PS2 and Vredestein Ultrac Sessanta.

Favorites are the GS-D3s and the Ultrac Sessantas. Good ride, good on the track, handles well under all situations and both are excellent in the rain.

Won't go back to 15s.

I think that the ride on 17s is comfortable, much more solid and generally the technology and compounds are greatly updated from the 15 varieties. The 15 Avons are mentioned and the exception to this but the longevity is a bit short from what I've heard.

Just for reference my experience is 60k miles, multiple track events, long distance (4,500 mile trips 3x) lots of rain, and a bit of snow.

Jim

Jim

[Paintwerks]

My Cobra will be finished early in the new year and I'm running the 15” Avon CR6ZZ's with about 600hp (supercharged). Darryl is doing the same setup with his supercharged FPV 335GT motor in his Pace Cobra.

For me，it's very much about the look. To each their own however but I don't like the look of Cobras with 17” or 18” wheels. The reason I went with the Avons is because they're hands down the best 15” road legal tyre currently available.

[MikeFromPerth]

Thanks everyone!

[albanycobra]

I went from 17's to 15's with Avon 6ZZ's. With the stroker 414 engine they hook up awesome. I also raised my spring rates front and rear to counter the softer tyre walls. The cars still feels tight and corners flat. The car drives better on the road and I cant wait to get to the track and really load these Avon tyres.

[RallySnake]

I have burned up many sets of 15 inch tires on my Arntz. Last year, I replaced the old MGB front suspension with an all new unit designed by Bill Guzman. I run long distance rallies in my car so comfort is important. I used Mickey Thompson's last time and just switched to Cooper Cobra's. They feel exactly the same and are cheap, comfortable, long lasting and give lots of grip. The thing I really like is that you can push the car into a slide and the breakaway is gradual and controllable. We won the 10 hour Midnight Run Rally on these tires and that went over Sherman Pass in Sequoia National Park.

[Treeve]

Better acceleration, less rotational inertia and lighter suspension with 15"s.

I run 17"s on the road and 13"s on the track. 17"s knock between 0.5 - 1s off my 0.60 time. Rolling diameter is nearly identical.

[boxhead]

Cobra ownership for me is all about the looks.
I built my car with 17 inch wheels initially, the car handled and drove very nice, a little rough on the road due to minimal sidewall flex.


An opportunity came to buy a suitable set of 15 inch rims, I took a gamble and bought a set of BillBoard tyres (these have a larger rolling diameter and bulging sidewalls than a "normal" 15 inch tyre).
The car now tram lines, rear tyres just scrape (easy enough fix) and I can not go any bigger with my rear brakes.
But by fark it looks a $hit load better (IMO)