18" alloys on a W202?

[bigjobby01]

I have a 1997 C200 and am thinking of putting bigger alloys on it. At present there are 15" alloys on with 195 65 R15 tyres. Is it possilble to fit 18" alloys to this model (not with the same tyres of course)? Are there any draw backs to fitting too large a wheel?

Thanks

 

[Flying Scot]

well bigger wheels will mean a lower profile tyre which will sharpen up the steering response but also firm up the ride. Provided you have the clearance from the suspension and wheel arches i cant see any other problems. We have 19" wheels on the SL500 which started off with 16" and then in later years 17" wheels and i think the new model has a 20" option.

regards

David

 

[clive williams]

I have a 1997 C200 and am thinking of putting bigger alloys on it. At present there are 15" alloys on with 195 65 R15 tyres. Is it possilble to fit 18" alloys to this model (not with the same tyres of course)? Are there any draw backs to fitting too large a wheel?

Thanks

Hi,

If you're thinking of fitting 18" wheels then you are going to require a 45 aspect ratio tyre for a 200mmish width. You don't say what width of rim you intend to fit but I doubt it will be much more than the 6/7J? you have at present. Don't be conned into thinking that the 18" diameter wheel imparts any better roadholding or handling because it won't. It will be there for looks alone.
IMO its all about all pose and no goes!

Clive

500E
E320CDIT210

 

[Flying Scot]

Hi,

If you're thinking of fitting 18" wheels then you are going to require a 45 aspect ratio tyre for a 200mmish width. You don't say what width of rim you intend to fit but I doubt it will be much more than the 6/7J? you have at present. Don't be conned into thinking that the 18" diameter wheel imparts any better roadholding or handling because it won't. It will be there for looks alone.
IMO its all about all pose and no goes!

Clive

500E
E320CDIT210

cant quite agree there you will have a bigger tyre to road footprint and stiffer sidewalls so both the handling (steering will be sharper more positive) and your roadholding (ultimate grip) will improve.

 

[Blobcat]

You can compare the various wheel/tyre options you want to try on the attached web site. http://www.tyresave.co.uk/tyresize.html
Put some 20" rims on with 245/30 if you want the looks Dammed uncomfortable though and very likely to crack them on pot holes. They will also do nothing for the handling.

 

[Blobcat]

cant quite agree there you will have a bigger tyre to road footprint and stiffer sidewalls so both the handling (steering will be sharper more positive) and your roadholding (ultimate grip) will improve.

Not neccessarily. As the susspension will have more work to do as the tyre is doing less. You can find that the wheel would be in less contact with the road. Wide tyres only provide increase grip on dry roads, try a newer 4x4 on wide wheels off road to test this theory.

 

[clive williams]

cant quite agree there you will have a bigger tyre to road footprint and stiffer sidewalls so both the handling (steering will be sharper more positive) and your roadholding (ultimate grip) will improve.

I knew I would open up this discussion again

The footprint can't be bigger as the rolling radius is the same for the same width tyre. Indeed, the footprint of the higher sidewall tyre ought to be bigger as the deformation is greater.

Check out the aspect ratio on formula racers where there is little restriction on tyre/wheel combinations and you will find the the aspect ratio is usually not less than 40% until they become enormously wide.

Clive

500E
E320CDIT210

 

[bigjobby01]

Thanks for the help.

 

[Flying Scot]

I knew I would open up this discussion again

The footprint can't be bigger as the rolling radius is the same for the same width tyre. Indeed, the footprint of the higher sidewall tyre ought to be bigger as the deformation is greater.

Check out the aspect ratio on formula racers where there is little restriction on tyre/wheel combinations and you will find the the aspect ratio is usually not less than 40% until they become enormously wide.

Clive

500E
E320CDIT210

The footprint must be bigger as if you increase the diameter of the wheel you will need to increase the section width and reduce the section height to maintain your rolling radius - so you will go from something like 195-55 to 215/225-40 ergo a wider tyre with a bigger footprint without even considering mounting it on a wider wheel. Then when you change to a bigger wheel you will most probably increase the J dimension as well so you will be increasing the effective footprint again. As to F1 tyres well so long as you are happy fitting new tyres every 50 miles then follow the F1 route - introducing F1 tyres into this discussion sounds like the ultimate red herring to me. As to deformation on a tyre with a higher profile it will indeed deform more than a low profile tyre under centrifugal force reducing the size of the footprint. To come back into the real world - perhaps you can explain why all the real 'performance' cars are using lower and lower profile tyres with bigger and bigger wheels if using high sidewall tyres would give an increased performance (roadholding - grip - and steering) benefit - somehow i think not

 

[Flying Scot]

The footprint must be bigger as if you increase the diameter of the wheel you will need to increase the section width and reduce the section height to maintain your rolling radius - so you will go from something like 195-55 to 215/225-40 ergo a wider tyre with a bigger footprint without even considering mounting it on a wider wheel. Then when you change to a bigger wheel you will most probably increase the J dimension as well so you will be increasing the effective footprint again. As to F1 tyres well so long as you are happy fitting new tyres every 50 miles then follow the F1 route - introducing F1 tyres into this discussion sounds like the ultimate red herring to me. As to deformation on a tyre with a higher profile it will indeed deform more than a low profile tyre under centrifugal force reducing the size of the footprint. To come back into the real world - perhaps you can explain why all the real 'performance' cars are using lower and lower profile tyres with bigger and bigger wheels if using high sidewall tyres would give an increased performance (roadholding - grip - and steering) benefit - somehow i think not

from Auto enginerering plus

German engineering gone wrong - somehow i think NOT

For example, the suspension on the new Boxster is essentially the same as the previous model, the only difference being that where it used to be very good, the suspension is now near perfect. Porsche engineers have meticulously checked every detail. So, as well as there being a reduction in weight on individual components, the new Boxster also gets a wider track and bigger tyres and wheels’, ensuring the drive becomes even more dynamic. The springs, dampers and anti-roll bars have all been reset to better fit the geometry of the new Boxster’s chassis and suspension. This, combined with the larger and wider tyres, amounts to less sway and roll.

Now i know they were looking at the complete concept BUT if you want to sharpen up your ride handling and the dynamics of driving your car as well as maybe making it look a bit more sexy AND you fully understand the downside - a rougher ride (i never drive over a depressed manhole cover for instance 35 profile tyres on the SL500) with some tramlining - something i get on the Volvo with 40 section tyres but never on the Merc or The MR2 both with 35 section tyres then go for bigger wheels and lower profile tyres. If you want a soft smooth floating ride out of your Merc then stick with the factory specified rubber. Also (try this for a contentious point ) you should get better fuel consumption as you are wasting less energy in flexing and heating the sidewalls and your rolling resistance will have consequently reduced - your life - your choices - your car

 

[Flying Scot]

You can compare the various wheel/tyre options you want to try on the attached web site. http://www.tyresave.co.uk/tyresize.html
Put some 20" rims on with 245/30 if you want the looks Dammed uncomfortable though and very likely to crack them on pot holes. They will also do nothing for the handling.

HO HUM i have 295/30/19 on the rear on Brabus MONOBLOCK VI wheels and while i dont go looking for worn out roads to drive on for sure i would not deliberately drive through a pot hole - not because i am worried about either the tyres, wheels or the car - but because i would not do that deliberately to any car. The car is far from uncomfortable in ride terms and very sharp in handling terms - not had her on a track 'YET' to discover if i can find out where the limits are or or what it is like with the esp switched off or even when the roll bar will deploy if i can get the car sideways but for sure that is on the cards and i have absolutely no doubt that my car would run rings around any other SL500 on the standard rubber and having driven quite a few SL500's before i bought this one i can assure you i dont notice a deterioration in the ride quality. In fact having driven a lot of soft top cars i am quite amazed that the car is so solid with the hood down no scuttle shake doors squeaking and other funny noises as the body flexes - all in all a somewhat awesome car looking and hadling even better on bigger wheels with low profile rubber Now any one got a spare set of 19" wheels for an SL 500 with slicks ?

 

[clive williams]

The footprint must be bigger as if you increase the diameter of the wheel you will need to increase the section width and reduce the section height to maintain your rolling radius - so you will go from something like 195-55 to 215/225-40 ergo a wider tyre with a bigger footprint without even considering mounting it on a wider wheel. Then when you change to a bigger wheel you will most probably increase the J dimension as well so you will be increasing the effective footprint again. As to F1 tyres well so long as you are happy fitting new tyres every 50 miles then follow the F1 route - introducing F1 tyres into this discussion sounds like the ultimate red herring to me. As to deformation on a tyre with a higher profile it will indeed deform more than a low profile tyre under centrifugal force reducing the size of the footprint. To come back into the real world - perhaps you can explain why all the real 'performance' cars are using lower and lower profile tyres with bigger and bigger wheels if using high sidewall tyres would give an increased performance (roadholding - grip - and steering) benefit - somehow i think not

David,

Let me take your points in order:

1) Given that it is eminently possible to purchase a 205x40x18 tyre then the foot print must be the same as a 205x65x16 tyre. The diameter and width of the tread is the same in both cases. However, the sidewall stiffness is less on the higher aspect ratio and therefore I would expect the deformation to be greater elongating the contact patch.

2) Increasing the width of the wheel (the J No.) has little if any bearing on the width of contact for acceptable widths. Check out the tyre manufacturers full specifuication charts and you will see that only one contact width is quoted for the range of acceptable rim widths. Conversely, go larger than the rim width range and the tread pattern compresses narrowing the contact patch and closing the grooves. Go narrower than the rim width range and the tread becomes convex also with a narrow contact patch.

3) The reference to formula tyres was to demonstrate that where there is little if any restriction, ultimate performance is achieved with relatively tall aspect ratios.

4) Centrifugal deformation should be about the same for low/high aspect tyres as it is the tread which bulges in bending in extremis, the tyre wall is in tension and deformation is minimal. All this happens at speeds far in excess of the tyres capabilities.

5) Wheel diameters on most hi-perf cars are dictated by the need to accommodate large diameter brake rotors and their calipers. The overall diameter of the tyre is often dictated by the bodywork (lower bodywork = better aerodynamics). The bit between the wheel rim and the o/d is the tyre! Additionally, lower profile tyres add the bling! factor to the car designers renderings.

You will no doubt admit that the Lotus Elise is one of the worlds best handling cars and it utilises 175/55/16 front tyres and 225/45/17 rears. If large diameter tyres with rubber band wheels = perforamnce then why has this car relatively tall tyres?????

Clive

500E
E320CDIT210