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Bigger tires (tyres) are for ego (***** envy) and is only good to a certain point. For most of us that simply want performance but with an adequate street ride, low profile tyres are only good to a certain point. After that, you might as well have solid rubber with no air inside. I'm running 18" Twists and I feel that to keep the proper diameter for speedometer accuracy and still a decent ride, I've used TireRack for research into the best selection.
My '86 951 has Hankook rubber.
Bigger tires (tyres) are for ego (***** envy) and is only good to a certain point. For most of us that simply want performance but with an adequate street ride, low profile tyres are only good to a certain point. After that, you might as well have solid rubber with no air inside. I'm running 18" Twists and I feel that to keep the proper diameter for speedometer accuracy and still a decent ride, I've used TireRack for research into the best selection.
My '86 951 has Hankook rubber.
The automotive industry gone bigger and bigger on wheel Diameter and then only wider with each diameter increase ?
The offsets numbers have gone higher
Street cars have got heavier and more powerful, hence Brake discs have gone bigger and the wheels no choice to be larger to fit over large brake discs ? or is it just fashion, the look and the marketing ?
Formula 1 cars are the fastest 4 wheeled vehicles in circuit racing...
Why then didn't an 18" set of wheels with smaller profiles make the car handle better ?
R
The fad for big wheels with skinny tires started about the same time that the British Touring Car Championship went for rules that defined minimum bodywork height by the rule "must not touch the ground with a flat tyre".
Voila - big wheels and low-profile tyres, driven by aero requirements.
The "tuning" fraternity followed, fashion follows racecar trends. Remember the number of turbocharged cars that came out in the '80's, when F1 was turbocharged? Then road car manufacturers went to V10's when F1 went to V10's?
Road and Track (IIRC) did a test with a Honda Accord fitted with stock 14" wheels, then went up sizes on wheels but kept the same rolling diameter and tyre section width. Best handling was on 15" wheels, worst on 18" (largest).
The same look-good-work-bad disease that's attacked the seats has also infected the Corvette's chassis through its tires. This is the second year the options list has advertised a set of P255/60R-15 Aramid-belted, radial-ply, white-letter tires. These Fat Alberts cost an extra $226.20 over the base P225/70R-15 steel-belted, radial-ply, blackwall rubber, so the natural conclusion is that they're the Hot Tip. Not so. We were advised against ordering the optional tires on our test car—the engineers openly admit their virtue is strictly cosmetic—but we wanted to try them anyway. We agree they add to the Corvette's macho-muscle look, but after riding on them for a thousand miles, we'll stick with steel belts. The 60-series radials are a lot like unruly kids—they have to be seen and heard. The tread has something to say all the time—an incessant whir over smooth pavement, a dull roar over textured asphalt, and a howl if you ask them to bend you through any turn at more than half-g determination. On the skidpad, they start to slide at 0.74 g, which is a far cry from the 0.83 g we left the Corvette at last year. In all fairness, the previous test was on well-worn steel-belted radials, while the 60-series rubber was barely scuffed in, but there should be no doubt in your mind which tires is for cornering and which is for cruising.
I had a 1980 Corvette with B.F.Goodrich 255/60-15 T/As. That car had the ride and handling of a shopping cart. Yet I miss it.
Interesting about the flat tyre thing........What year was that Mike ?
I'm in no doubt smaller profile for racetracks is far superior for handling.
A 944 on 15" and 60 series compared to 17" and 45 series would be much better / tighter with less rock and roll, but a lot also depends on the compound...so a 15" soft slick should be as good if not better than an 18" road tyre set up...?
As I've worked at a wheel & Tyre shop for the last 8 years, and in this time owned a 968, x2 924's and x4 944's I changed all of them from 15" to 18" and tried all the variants on the street...and the results mostly favour the smaller sizes..
Initially when I changed to a bigger diameter and smaller profile the car feels more pointy and direct but also seems more twitchy and follows road contours, cambers and bumps which is not a good feeling.. traction also suffers......as there is less flex and compliance in the tyre..
Every time I changed from a 16, 17 or 18 back to a 15" due mostly to the lighter weight the cars always felt quicker acceleration and the turning feel is so much nicer / comfortable on 60 series tyres...for sure the roll is more evident but I don't know many / any cars other than the 24 /44 /68 chassis that "love" and feel happy when you push them harder into corners....so this creates more fun and feel and the grip is there too....
For My project 924s 2.7 I've decided to go (one inch up) at 16" with 55 series, and skinny 205mm all round also 7x16 all round for weight & low resistance reasons, also the ride and compliance.
I 'm aware that the 2.7 motor will have some good torque and may / will have some wheelspin (Dependant on how much right foot application) but for me this is the challenge....to feed the power in nicely , or also to be in a higher gear and I hope the low resistance and weight of this 16" wheel & Tyre combo will benefit the speed / acceleration and cornering of the car....
I may be wrong ! it may be too skinny a rear tyre where It's hard to not wheelspin? I dunno, but this is where I'm gonna start first and see.
I'm basing this theory & idea also on my original 924s tyres & Wheels which were all 6x15 and 195/65/15 and this car was without doubt a faster car than a 944 I had also at the same time on 215/60/15 and 7x15's......
I have also experienced many occasions where a small hot hatch turbo car with 19" wheels and 35 series tyres has sat there at the traffic lights spinning wheels when the lights go green and any 924 / 944 and easily a 968 all have great traction and has left the hatch for dead!
R
I went with a set of four 17x7 wheels with 225 series rubber for much the same reasons. I could have used the 17x9s I also have with much wider 255 series tires but it would have added nearly 40lb of rotating, unsprung mass to the car. I do get some wheelspin but only when hard into a corner and hard on the gas -i.e., I have to be trying to make it happen. I still have the option of using stickier tires as I currently only have high-performance all-seasons mounted.
On the scale, there isn't a significant weight difference between the 17" summer wheels/tires and the 15" winter wheels/tires, but the weight of the 17s is farther from the hub so they do end up being a bit slower-feeling.
I do appreciate the sharper handling from the lower-profile tire but I doubt that ultimate grip would be much different between a 15" tire and 17" tire of equal diameters, widths, and compounds. If anything, I would probably guess that the 15" tire might have a little more, as noted above.
I have a set of 18 inch wheels on my car with 265 wide street semi slicks all round. Not only do they look awesome, but they totally transformed the handling of the car. I shaved almost 4 seconds off my old track time done with a set of 16 inch fuchs and street tires. Kind of an apples to oranges comparison, but I love the handling with the new wheels and tires, and I would never go back to the tiny 16 inch bicycle wheels. Now I can easily pull 1.2 G's on flat corners on track. When I get some more money together I'd like to get a set of lighter 18's with proper semi slick tires and dedicate those to track use.
Here's what I currently have, compared to the tiny tires on the old Fuchs wheels.
This isn't even apples to oranges, it's more like apples to straw hats. I would argue that the larger side wall on a F1 car is for effective spring rate.
This isn't even apples to oranges, it's more like apples to straw hats. I would argue that the larger side wall on a F1 car is for effective spring rate.
Incorrect. The larger sidewall in F1 is because it is mandated in the rules.
12-29-2015, 02:19 PM
