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Wheels vs Suspension

LouG

Active Member
Dec 1, 2017
1,328
476
Nelson, New Zealand
I don't understand that? If the body of the car rolls, the centre of gravity moves towards the outside and loads up the outside tyres more. I thought the whole point of keeping a car flatter was to keep the weight more evenly distributed on the wheels and keep the tyres closer to vertical. Otherwise, what is the point? And I don't see how this would be a benefit in the dry but a disadvantage in the wet. The principals are the same.

Anyway, I'm not asking about how to upgrade my car. It's a hypothetical question about the relative importance of wheels/tyres vs suspension itself.
In the wet the suspension has to work the same way as the driver, transitions have to be smooth and controlled to prevent sudden loading of the tyres and maintain grip. Stiffer bars load the weight bearing wheels too suddenly and it's difficult to reach peak traction without overdoing it.
There is less feel for the margins of grip too.
I noticed the difference with adjustable Konis on my MX5, it was far more predictable in the wet with them set softer.
 

Mr Pig

Active Member
Jun 17, 2015
1,473
399
I'd argue tyres are the most important thing to change first.
Again, surely it depends on what you already have? I do have to laugh at the guys I know who buy sporty cars, fit the biggest wheels they can fit under the arches then look for the cheapest tyres they can find!
 

Deleted member 103408

Guest
Yes it does depend on what you already have, the time of year (summer or winter tyres) and what else you are doing to the car.
 
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Damo H

Carbon Snob
Staff member
Moderator
Oct 3, 2012
3,760
2,213
Car Length In Front
Again, surely it depends on what you already have? I do have to laugh at the guys I know who buy sporty cars, fit the biggest wheels they can fit under the arches then look for the cheapest tyres they can find!
Yes it does, but very few manufacturers will stick the best rubber for the car.

You only have to read a review of my car, one of the comments was that it was fitted with the old Contis (5P) which were hardly a great tyre in the time. The newer better ones (6) would of been at least nice when the inner door card even tells you what pressure for the race track.

So always start with getting the best tyres first. BBK, Suspension mods are irrelevant if you've got Nankang Ditchfinders. If you're changing your wheel size, then get the decent rubber at the start, and make sure you get light (but strong) wheels.

One of the best mods I did to my MINI was going from some very nice looking R95 Double Spoke 18" MINI wheels with Falken Tyres to some OZ Ultraleggeras with some Yokohamas. It saved nearly 4kg a corner of unsprung weight as the wheels and tyres where lighter. Not even going to get into rotational weight.

Once you have decent lightweight wheels and tyres, you can then look to mod your suspension and brakes. Personally I went with brakes first on the MINI. No point having decent brakes without decent tyres though. Purpose of a BBK isn't to stop you any faster, that's limited by the grip of the tyres, but to reduce brake fade. The standard Cupra 340mm kit is very good considering, but its nice having the shiny Brembos.
 
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Mr Pig

Active Member
Jun 17, 2015
1,473
399
Yes it does, but very few manufacturers will stick the best rubber for the car.
Years ago I thought they matched the tyres to the desired performance characteristics of the car but they clearly don't. Not very often anyway. They obviously just fit what they get a deal on. I've seen cars of the same model in the forecourt with different tyres on and more recently I've noticed budget brand tyres on new cars, which is something you would not have seen twenty years ago.

Talking of weight, what would be lighter, all else being equal. A larger wheel, lower profile tyre or bigger tyre on a smaller wheel?
 
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Damo H

Carbon Snob
Staff member
Moderator
Oct 3, 2012
3,760
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Years ago I thought they matched the tyres to the desired performance characteristics of the car but they clearly don't. Not very often anyway. They obviously just fit what they get a deal on. I've seen cars of the same model in the forecourt with different tyres on and more recently I've noticed budget brand tyres on new cars, which is something you would not have seen twenty years ago.

Talking of weight, what would be lighter, all else being equal. A larger wheel, lower profile tyre or bigger tyre on a smaller wheel?
In my experience larger wheels and low profile tyres are heavier, but all depends on the design and manufacturing process of the wheel.

For example, these 17” wheels on the MINi where heavy AF, something like ~13kg..

F5528AD9-C525-48E9-9CBB-3A9CB53FC47C.jpeg


So much so even the 18” OEM wheels and tyres where lighter at ~11kg...

29AE6F66-BB59-45CE-84FC-40AA4F2EA78B.jpeg

DEBEFE31-CDA6-429A-BD08-03ED823C69D9.jpeg


But the Suoerleggeras where 7.9kg a wheel from memory.

BEA07F39-1004-4846-9576-2FB1642EA5E5.jpeg


Sorry for all the MINI photos but I did have 3 haha!

Anyway if you’re going from say OEM 18” wheels to aftermarket 19” wheels, you could possibly save weight just by buying a decent light wheel. OZ Racing Uktraleggera HLT are a good example. But Rays are better as they’re forged, at about £1,000 a wheel though lol.
 

CupraGeezer

Active Member
May 11, 2018
255
106
Talking of weight, what would be lighter, all else being equal. A larger wheel, lower profile tyre or bigger tyre on a smaller wheel?
For a given design, an increase in wheel diameter will result in a significant increase in weight due to the larger radius, and hence circumference, of the rim (the heaviest part of the wheel). The slight saving in tyre weight due to the lower profile is nowhere near enough to offset this increase.

Of course, a change from a "standard" wheel to a superleggera will give a significant weight saving, as @Damo says.
 

Damo H

Carbon Snob
Staff member
Moderator
Oct 3, 2012
3,760
2,213
Car Length In Front
For a given design, an increase in wheel diameter will result in a significant increase in weight due to the larger radius, and hence circumference, of the rim (the heaviest part of the wheel). The slight saving in tyre weight due to the lower profile is nowhere near enough to offset this increase.

Of course, a change from a "standard" wheel to a superleggera will give a significant weight saving, as @Damo says.
You may in fact find a lower profile tyre is just as heavy if not heavier due to increasing the strength of the side wall. These days it’s hard to find the quoted tyre weight.
 

CUPRoAr

Active Member
Oct 7, 2017
67
14
You may in fact find a lower profile tyre is just as heavy if not heavier due to increasing the strength of the side wall. These days it’s hard to find the quoted tyre weight.
Use tirerack.com, i have found they have most of the uhp tyres available and they list the weights in all profiles and sizes.
 
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Deleted member 103408

Guest
Very happy with mine, look good and save weight on the stock wheels.
 
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Pinky

Active Member
Sep 27, 2015
186
6
Suspension controls handling via its affect on physics. Wheels/tyres react to various shifting forces/weight that are allowed to get to them by the shocks, springs, roll bars, strut bars, bushes etc.

All other things being equal, and running the same wheel/tyre package, a vehicle with sorted suspension will handle better than one with stock suspension.
 
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