Disadvantages of bigger diameter & lower profile (Heavier wheels)
- Thread starter 924Srr27l
- Start date
vitesse
Active member
Don't forget ,Dave that some of us mere mortals hurl our lightweight 924S's around Oulton,Donnington & Anglesey on trackdays using half worn good quality used tyres as fast as we can without melting them (clearly lack of talent!) although tyre pressures do rise ,in my case upto 10 psi in a day- apart from sprint days at Curborough when there's not enough time to get them that hot-I just use the standard 195/65-15" tyres on 924 Turbo wheels.
However ,faced with this discourse ,I shall be be too scared to try again without radical wheel & tyre surgery.[&o]
However ,faced with this discourse ,I shall be be too scared to try again without radical wheel & tyre surgery.[&o]
924Srr27l
New member
On this Wheel & Tyre Theme (Bigger & Wider) is next years F1 Regs are up for a
big change in Wheel and Tyre width and also more Aerodynamic downforce, which they predict these new car's will be 1-5
seconds faster in lap times compared to this year...
On very fast (straights) tracks like Monza it's said that such is the extra Drag of the Wider wheels lap times
will not be that much quicker than this year, but on other slower and tighter circuits the extra downforce and
rubber molecules will provide faster corner speeds.
This Picture clearly illustrates, how the car's may look (This years car modified)
where the wheels are so large it makes the chassis look small but with 4 HUGE lumps hanging off it!
No wonder the Drag is a big factor.
F1 did consider changing up from the current 13" to an 18" Rim but testing revealed many issues:
Mercedes’ executive director technical Paddy Lowe said:
"The subject of bigger wheels has been raised many times over the last five or eight years,” he said. "But I think the broad consensus is that going to bigger wheels is not a good direction.”
"Certainly from a grip point of view it’s not positive, like-for-like such tyres will have a lower grip and the weight will go up considerably.
So it’s not an attractive direction performance-wise. So I think generally we would intend to stick with the 13-inch wheels.”
R
big change in Wheel and Tyre width and also more Aerodynamic downforce, which they predict these new car's will be 1-5
seconds faster in lap times compared to this year...
On very fast (straights) tracks like Monza it's said that such is the extra Drag of the Wider wheels lap times
will not be that much quicker than this year, but on other slower and tighter circuits the extra downforce and
rubber molecules will provide faster corner speeds.
This Picture clearly illustrates, how the car's may look (This years car modified)
where the wheels are so large it makes the chassis look small but with 4 HUGE lumps hanging off it!
No wonder the Drag is a big factor.
F1 did consider changing up from the current 13" to an 18" Rim but testing revealed many issues:
Mercedes’ executive director technical Paddy Lowe said:
"The subject of bigger wheels has been raised many times over the last five or eight years,” he said. "But I think the broad consensus is that going to bigger wheels is not a good direction.”
"Certainly from a grip point of view it’s not positive, like-for-like such tyres will have a lower grip and the weight will go up considerably.So it’s not an attractive direction performance-wise. So I think generally we would intend to stick with the 13-inch wheels.”
R
924Srr27l
New member
944 man said:
This thread didn't ask a Question ? or did I have any questions to ask you from your point regarding Gyroscopics,
This post is also discussing the tyre profile also, not just the unsprung wheel & Tyre weight.
Do you have anything else to add ? if so lets hear it, How about a description on how the Gyroscopic
effects contribute or adversely affect a car's handling ?
If not you can join the "Foolish" other few that also do nothing much else
apart from mock and declare "my car's planted on large wheels" and "Why do they put fat tyres on racing cars" etc...!
It's entertaining!
R
graham tompkins
New member
Guys, this thread is getting Wheelie Tyresome !!!!
Why can't you "foolish few" ,listen to your expert, and rather than waste his time with your pointless questioning of his indisputable expertise, and spend your time and efforts on improving your inadequate excuses for track day cars, and improve your driving techniques.
G
Why can't you "foolish few" ,listen to your expert, and rather than waste his time with your pointless questioning of his indisputable expertise, and spend your time and efforts on improving your inadequate excuses for track day cars, and improve your driving techniques.
G
924Srr27l
New member
Waylander said:
Yeah I agree, but conversations only turn into a slanging match when people that either don't, or won't? understand some technical characteristics and occurrences and also comments like yours about this technical subject should not be on this forum but another one for budding F1 lovers is not helpful at all but negative and it only adds fuel to the fire, doesn't it?
There are many people that have experienced the downsides of bigger wheels, and they don't need to post this. Some of them will be brave and add their experiences but others I'm sure will be put off that they are also likely to come under siege from a few sceptics.
It should be a post full of learning and fun! but there will always be a clash from some car lovers than modify their cars
extensively beyond boundaries that actually make the car worst and slower will never understand or agree to this.
Have you ever read or seen anywhere any manufacturer's & retailers marketing that is promoting "Make your car slower" !?
"Increase your 0 - 60 times" and "Make your car handle like a shopping trolley on black ice" etc...?
It would be funny! but it doesn't happen and an emphasis on "performance" and "Racing" is the norm to sell lots of products.
Do Huge rims look Cool, Too right they do...........when they have been designed for the car
R
Monkeythree
New member
FFS man can you not take a hint? You've got half a dozen knowledgable and respected forum members trying to tell you to stop flapping your gums and each time you come back with more cut and pasted pish. Take some advice and lie low for a while.
Monkeythree
New member
Beyond help
edh
New member
I'd rather hear from an expert...
But i'd always thought that to reduce understeer you should add grip at the front or reduce it from the rear.
So for the front, It's either a
1.wider tyre with a lower profile
Or
2. A narrower tyre with a higher profile
Hmmm... how many people would choose 2. ?
btw Your golf figures quote improved braking and lateral g numbers for bigger wheels/lower profile tyres.
If you read page 1, I agree with some of what you wrote. But there's no discussion or debate, just a constant assertion of your sacred truths.
But i'd always thought that to reduce understeer you should add grip at the front or reduce it from the rear.
So for the front, It's either a
1.wider tyre with a lower profile
Or
2. A narrower tyre with a higher profile
Hmmm... how many people would choose 2. ?
924Srr27l said:
btw Your golf figures quote improved braking and lateral g numbers for bigger wheels/lower profile tyres.
If you read page 1, I agree with some of what you wrote. But there's no discussion or debate, just a constant assertion of your sacred truths.
924Srr27l
New member
Here's a schematic diagram which illustrates the weight of all the Unsprung weight
(Wheel / Tyre / Brakes / Suspension) is double the force when subjected bumps.
Reducing unsprung weight is the key to improving handling, and Increasing it with heavier wheel & tyres is decreasing the handling.
The lower the unsprung weight, the less work the shocks and springs have to do to keep the tires in contact with the road over bumpy surfaces. Lot of problems, if not all of them is caused by inertia. Bigger weight means higher inertia. Higher inertia means more workload for shocks and springs to keep tyres on the ground.
If unsprung components have a high mass they are harder to accelerate/decelerate and thus it is more difficult for the suspension to maintain a consistent tyre load.An easy way to reduce unsprung weight and improve traction is to fit lightweight wheels.
R
924Srr27l
New member
edh said:
Yes the whopping 19's produced very small amounts of increased figures (lat and braking), not enough to make them a consideable improvement, but acceleration suffered by some margin.
Add all the characteristics together (Go, stop & Corner) and we;re talking ROAD use here, and a back to back test on 15's then 19's in this car for some people would show up the disadvantages.
Fitting a Mid engined Tyre set to a front engined car will of course change the balance,
255's are overkill on the rear and 205 front too narrow for those that "Push hard" normal driving should be fine and present no issues. If the Push driver wants to rid the understeer change the rears to 205 wide tyres then you'll reduce the understeer.
R
944Scott
New member
A lot of cars are weekend vehicles for their owners, for those with larger wheels the trade off between driveability and looks is acceptable compromise and for some part of a modification as to how they think their vehicle should have looked when it left the factory (myself included) I went from turbo twists to cup 1's for no noticeable difference to how the car performed. Anyway I have found some new wheels for my ride, what do you think pretty rad eh [
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