Why big wheels!!!
Discussion
My fiancee has a ZR160, ( I have the Chim 450). When driving to Cheltenham today in her ZR, I thought to myself how stupid it was that MG take the trouble to lower the suspension to achieve a decent ride height, only to negate this by putting on stupidly oversized 17" wheels on them!!, thus making the ride height higher than a bog standard Rover model!! Why? is is just looks? I thought the idea of a 'hot hatch' was to give the driver a feel of a sports car in a normal car, I just felt I was driving a noisey car with damn near MPV ride height!!
Am I the only person who thinks the obsession with big wheels is a little silly, bordering on ruining the drive??
chris
Am I the only person who thinks the obsession with big wheels is a little silly, bordering on ruining the drive??
chris
Right:
a) Big wheels look better on most cars.
b) You can run a much lower profile tyre, thus improving the handling (not necessary of course if your car is already on 40-profile as standard like most TVR's seem to).
Of course it is possible to over-wheel a car (how many of you have seen a Corsa on 17's?, lol) but I have a Corrado and on that 17's look and drive a helluva lot better than the poxy little 15" ones the car came with.
All IMHO of course...
John
a) Big wheels look better on most cars.
b) You can run a much lower profile tyre, thus improving the handling (not necessary of course if your car is already on 40-profile as standard like most TVR's seem to).
Of course it is possible to over-wheel a car (how many of you have seen a Corsa on 17's?, lol) but I have a Corrado and on that 17's look and drive a helluva lot better than the poxy little 15" ones the car came with.
All IMHO of course...
John
The only reason an MG ZR feels so high is because of the seating position.
The drivers seat is adjustable, but only from "very high" to "pass the oxygen mask"
Although, I've just done some sums and the rolling diameter is actually an inch greater than standard boots on my old Rover 200vi
The drivers seat is adjustable, but only from "very high" to "pass the oxygen mask"
Although, I've just done some sums and the rolling diameter is actually an inch greater than standard boots on my old Rover 200vi
Good answers!
However, I still think the 17s on a super mini are still too big!! I can fully understand the larger wheels on larger cars, like the very nice BMW, but on an underpowered ZR160!! The brakes arn't all that brilliant either, very spongy, they feel exactly the same as the top of the range R25. You have to push the pedal half way down to get any kind of bite, which doesn't inspire 'hot hatch' driving!
I am not slagging off the ZR, I bought it with my own cash as the sensible family car, but, as with the TF160 I part exchanged for my Chim 450, I just find it a tad disappointing to drive, especially acceleration.
I remember a Golf deisel on my tail when driving the TF hard, and could not shake it off in any gear, using all the available revs, and that is a very heavy car with 150 bhp, (I think!!)I know thats hardly the point of having a fun sportscar, but the advertising MG does with its cars is a little optimistic regarding power!! After having the TVR for a few months now, the ZR feels even higher, and positively lethargic.
Having said that, it is still fun putting my foot down without worrying about the back spinning away from me!!
Chris
However, I still think the 17s on a super mini are still too big!! I can fully understand the larger wheels on larger cars, like the very nice BMW, but on an underpowered ZR160!! The brakes arn't all that brilliant either, very spongy, they feel exactly the same as the top of the range R25. You have to push the pedal half way down to get any kind of bite, which doesn't inspire 'hot hatch' driving!
I am not slagging off the ZR, I bought it with my own cash as the sensible family car, but, as with the TF160 I part exchanged for my Chim 450, I just find it a tad disappointing to drive, especially acceleration.
I remember a Golf deisel on my tail when driving the TF hard, and could not shake it off in any gear, using all the available revs, and that is a very heavy car with 150 bhp, (I think!!)I know thats hardly the point of having a fun sportscar, but the advertising MG does with its cars is a little optimistic regarding power!! After having the TVR for a few months now, the ZR feels even higher, and positively lethargic.
Having said that, it is still fun putting my foot down without worrying about the back spinning away from me!!
Chris
Why big wheels?
1. They look good (usually)
2. Generally fitted with lower profile tyres to a. look good and sometimes b. handle better (but that depends on suspension settings - it can make the ride too hard).
3. They look good
4. Allow bigger brakes (not always fitted though).
5. Look good.
6. They can charge you more.
7. They look good.
8. Tyre manfucturers like them 'cos of the expensive tyres you need to fit.
9. They look good
10. Bigger rims usually allows for wider rims as well so you can fit fatter tyres.
and did I mention they look better on most cars?
1. They look good (usually)
2. Generally fitted with lower profile tyres to a. look good and sometimes b. handle better (but that depends on suspension settings - it can make the ride too hard).
3. They look good
4. Allow bigger brakes (not always fitted though).
5. Look good.
6. They can charge you more.
7. They look good.
8. Tyre manfucturers like them 'cos of the expensive tyres you need to fit.
9. They look good
10. Bigger rims usually allows for wider rims as well so you can fit fatter tyres.
and did I mention they look better on most cars?
Reason for putting big wheels on cars like the Rover/Leon etc?
1) Looks
2) Looks
3) Looks
In terms of ride/handling there is no need for 18" wheels on cars such as these but it makes the car look tougher, after all that is half the appeal for a fast car...
edit: icamm - we seem to be thinking along the same lines...
>> Edited by egomeister on Thursday 2nd January 13:43
1) Looks
2) Looks
3) Looks
In terms of ride/handling there is no need for 18" wheels on cars such as these but it makes the car look tougher, after all that is half the appeal for a fast car...
edit: icamm - we seem to be thinking along the same lines...
>> Edited by egomeister on Thursday 2nd January 13:43
There's advantages and disadvantages to fitting larger wheels. Advantages are : Looks, higher levels of grip, more direct feel, can fit larger brakes. Disadvantages are : Cost, ride quality suffers, less progressive breakaway, tramlining often increases dramatically on TVRs too.
In addition, you may need to modify the suspension to allow for the larger wheel if your rolling radius has increased (stop the tyres catching arches etc)
In addition, you may need to modify the suspension to allow for the larger wheel if your rolling radius has increased (stop the tyres catching arches etc)
I agree that the big look great, but, from a strictly personel point of view, I despair that manufactures put looks way above driver involvement. I do not want to feel as if I need to call ground control before parking!! Surely nice looking 15 or 16" wheels look just as good without compromising the ride height!
As for fast cars, even though a Golf deisel kept up with me in my TF, I could keep up with a Celica 190 in it too! I am led to believe (from my own experience) that cars with around 140-190 bhp are not that much different in acceleration in the real world. Some are just better to drive than others!
As for fast cars, even though a Golf deisel kept up with me in my TF, I could keep up with a Celica 190 in it too! I am led to believe (from my own experience) that cars with around 140-190 bhp are not that much different in acceleration in the real world. Some are just better to drive than others!
I think the level of PAS helps to disguise tramlining by not feeding the turning force to the driver. Certainly there is a huge difference in TVR's with/without PAS. Just the fact that PAS cars are fitted with wider front tyres shows how much. The fact that the PAS cars still don't seem to tramline as much as the non-PAS cars tells even more.
roop said:........... In addition, you may need to modify the suspension to allow for the larger wheel if your rolling radius has increased (stop the tyres catching arches etc)
Yeah, but mostly they keep the rolling radius the same by fitting lower profile tyres.
ie on the Rover I changed from 185/55 R15 to 205/40 R17 which meant that the rolling radius was basically the same, but the sidewall flex was greatly reduced.
squirrelz said:
ie on the Rover I changed from 185/55 R15 to 205/40 R17 which meant that the rolling radius was basically the same, but the sidewall flex was greatly reduced.
Err, not quite, your new combo is 1.9% larger in rolling circumference, IMHO this may be a bit too much, I try to keep below 1.25%.
squirrelz said:Although, I've just done some sums and the rolling diameter is actually an inch greater than standard boots on my old Rover 200vi
If your sums are correct it would lead me to the conclusion that the MG is either geared differently to the Rover or has a recalibrated speedo.
Personally I'd hope that the former conclusion is correct for a 'sporting version' of the car.
Hi Chris
At the risk of getting numerous 'No Respect' ratings (though even that would be welcome since I don't have any ratings at all at the moment!
) I thought I would add my opinions to this. 
The non-aesthetics reasons for large wheels are as follows (this isn't meant to be an exhaustive list):
1. Allows the fitting of larger brake discs with the inherent advantages that brings (outright braking power improved, more consistent performance possible with repeated heavy braking).
2. Fitting lower profile tyres improves the handling in that the reduced tyre sidewall height reduces unpredictable/unwanted movement during cornerning.
3. Increased footprint. A large diameter tyre has a larger footprint than a smaller diameter tyre of the same width because the length of the (roughly) rectangular contact patch is increased. This can improve straight line and cornering traction.
4. Top speed considerations. Although fitting larger wheels/tyres (in terms of overall diameter) has a blunting effect on acceleration (shock horror!) it also has a positive effect on top speed, assuming this is allowed by total drag vs power, without having to change gear ratios, engine red line, etc.
Oh, and as icamm didn't make it clear enough, they look good.
The negatives are pretty obvious:
1. All other things being equal the ride height is increased, which in turn raises the centre of gravity.
2. The wheels can be heavier which adds to overall mass (blunting acceleration and braking), but the main downside of this is that unsprung weight is increased making the work of the suspension potentially more difficult and the gyroscopic effect of the increased wheel weight (and its greater distance from the centre of rotation) can affect the steering at high speeds.
3. Using lower profile tyres generally reduces the ride quality as much of the 'ride' of a car comes from the tyres.
4. The tyres can be bloody expensive!
5. There is a possibility that overall drag is increased by having large wheels, though I'm not sure about this and how big the effect would be. On open-wheel cars (e.g. F1) this can be a major consideration though.
I hope this helps to firm up some of the pros and cons somewhat.
Regards.
roadsweeper.
At the risk of getting numerous 'No Respect' ratings (though even that would be welcome since I don't have any ratings at all at the moment!
) I thought I would add my opinions to this. The non-aesthetics reasons for large wheels are as follows (this isn't meant to be an exhaustive list):
1. Allows the fitting of larger brake discs with the inherent advantages that brings (outright braking power improved, more consistent performance possible with repeated heavy braking).
2. Fitting lower profile tyres improves the handling in that the reduced tyre sidewall height reduces unpredictable/unwanted movement during cornerning.
3. Increased footprint. A large diameter tyre has a larger footprint than a smaller diameter tyre of the same width because the length of the (roughly) rectangular contact patch is increased. This can improve straight line and cornering traction.
4. Top speed considerations. Although fitting larger wheels/tyres (in terms of overall diameter) has a blunting effect on acceleration (shock horror!
) it also has a positive effect on top speed, assuming this is allowed by total drag vs power, without having to change gear ratios, engine red line, etc. Oh, and as icamm didn't make it clear enough, they look good.
The negatives are pretty obvious:
1. All other things being equal the ride height is increased, which in turn raises the centre of gravity.
2. The wheels can be heavier which adds to overall mass (blunting acceleration and braking), but the main downside of this is that unsprung weight is increased making the work of the suspension potentially more difficult and the gyroscopic effect of the increased wheel weight (and its greater distance from the centre of rotation) can affect the steering at high speeds.
3. Using lower profile tyres generally reduces the ride quality as much of the 'ride' of a car comes from the tyres.
4. The tyres can be bloody expensive!
5. There is a possibility that overall drag is increased by having large wheels, though I'm not sure about this and how big the effect would be. On open-wheel cars (e.g. F1) this can be a major consideration though.
I hope this helps to firm up some of the pros and cons somewhat.
Regards.
roadsweeper.
Yep. However, how often is this really done?
roadsweeper said:The non-aesthetics reasons for large wheels are as follows (this isn't meant to be an exhaustive list):
1. Allows the fitting of larger brake discs with the inherent advantages that brings (outright braking power improved, more consistent performance possible with repeated heavy braking).
True. It also normally makes the loss of grip sharper so a car will slide away with less warning and less controlability. Therefore it's less easy to catch a slide.
2. Fitting lower profile tyres improves the handling in that the reduced tyre sidewall height reduces unpredictable/unwanted movement during cornerning.
Not sure this is true but it's marginal if it is. A larger diameter tyre has a narrower contact point with the ground (front/back) and stiffer tyres so they don't "squash" as much it gets very marginal.(Try drawing to different diameter circles onto the same baseline. Then draw another line parrallel and slightly above the first. Which circle has largest percentage below the second line?)
3. Increased footprint. A large diameter tyre has a larger footprint than a smaller diameter tyre of the same width because the length of the (roughly) rectangular contact patch is increased. This can improve straight line and cornering traction.
You will possibly get slightly more grip, due to better tyre control onto a flat surface, before they slide but then a less controlable slide. This will normally lead to driving well within the limits of the tyre. You are also likely to get a much more jittery and jumpy ride on a poor surface leading to less grip.
One of the bigger factors is likely to be the fact that the bigger/lower profile tyres are of a sportier rubber compound and generate more grip than smaller/higher tyres.
Again this is marginal for road cars as you normally try to keep the rolling radius as close to original as possible. 1-2% increase in diameter (halve it for the radius increase) won't make too much difference to top speed.
4. Top speed considerations. Although fitting larger wheels/tyres (in terms of overall diameter) has a blunting effect on acceleration (shock horror!
Didn't I say that
Oh, and as icamm didn't make it clear enough, they look good.
. Oh yes so I did So I won't repeat them again
The negatives are pretty obvious:
. I do stand to be corrected on any of this if we have any real tyre experts in the forum. Edited 'cos some of what I said made even less sense than this :-).
>> Edited by icamm on Friday 3rd January 14:23
Edited again for spelling 'cos preview isn't working for me at the mo'.
>> Edited by icamm on Friday 3rd January 14:25
I like your list of good and bad points about larger wheels, most if not all make very good sence.
In the round up if it all, if you make the rim larger you change the profile to acount for the change in the overall diameter of the wheel or the distance it travels in one rotation.
If you use a rooler to look at a two cars, one in 15' wheeels and the other on 17' wheels there should only be a few minls difference in the hight but what will make the car on the 17's look different is the profile of the tyre to the gap between the tyre and the top of the wheel arch (have a close look at some cars the next time your passing and you will see what im on about) the gap should be slightly less than the profile of the tyre, this will make the car look as though the car is sitting at the right hight.
But the most important thing about a tyre whel combination is the width of the tyre, this is the area of the tyre that gives the grip.
This is the most ive ever typed :shit:
In the round up if it all, if you make the rim larger you change the profile to acount for the change in the overall diameter of the wheel or the distance it travels in one rotation.
If you use a rooler to look at a two cars, one in 15' wheeels and the other on 17' wheels there should only be a few minls difference in the hight but what will make the car on the 17's look different is the profile of the tyre to the gap between the tyre and the top of the wheel arch (have a close look at some cars the next time your passing and you will see what im on about) the gap should be slightly less than the profile of the tyre, this will make the car look as though the car is sitting at the right hight.
But the most important thing about a tyre whel combination is the width of the tyre, this is the area of the tyre that gives the grip.
This is the most ive ever typed :shit:
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