How much sidewall is enough?
Discussion
I've had a C220 Sport for a few years and, while a decent car, it has suffered at the hands of Buckinghamshire's roads, needing at least 5 tyres replaced before their time due to sidewall damage. That's the thick end of £1,000 in 30 months. We live in an unlit village and it is not always possible to see potholes, especially when it has been raining. It's a common theme at parish council meetings, but years of complaining have resulted in absolutely zero improvement.
Anyway, I'm determined that its replacement will be less susceptible so this got me thinking about "how much sidewall is enough"?
The W204 C-Class, in top 'sporty' (i.e. daft*) spec comes with staggered 18" wheels with the following tyres:
225/40R18 = 90mm nominal sidewall height
255/35R18 = 89mm nominal sidewall height
When you consider that Bucks County Council won't even consider filling in a pothole until its depth is almost half of this size of sidewall (40mm minimum, with sharp edges and at least 300mm in size), you can see why this might be a problem.
The obvious answer is a 4x4 and while I'd love a Discovery, no 4x4s are available or very attractive within my budget.
I think the W204's problem is just its age, the current equivalent spec 3 Series for instance has the same wheel sizes but one size up in tyre, meaning a useful extra 10mm in sidewall. Enough?
My thoughts are drifting to a 5 Series/E-Class as they tend to have even larger tyres again. For instance, a 535i M Sport has nominal 110mm sidewalls on its standard 18s. Plenty?
How much sidewall is enough?
*Before anyone says "well, buy a spec that has 16" wheels", Mercedes will only sell a very odd, limited model with small wheels, and to spec that up to an equivalent standard as the higher-spec models is financial suicide. Besides, they look pants
Anyway, I'm determined that its replacement will be less susceptible so this got me thinking about "how much sidewall is enough"?
The W204 C-Class, in top 'sporty' (i.e. daft*) spec comes with staggered 18" wheels with the following tyres:
225/40R18 = 90mm nominal sidewall height
255/35R18 = 89mm nominal sidewall height
When you consider that Bucks County Council won't even consider filling in a pothole until its depth is almost half of this size of sidewall (40mm minimum, with sharp edges and at least 300mm in size), you can see why this might be a problem.
The obvious answer is a 4x4 and while I'd love a Discovery, no 4x4s are available or very attractive within my budget.
I think the W204's problem is just its age, the current equivalent spec 3 Series for instance has the same wheel sizes but one size up in tyre, meaning a useful extra 10mm in sidewall. Enough?
My thoughts are drifting to a 5 Series/E-Class as they tend to have even larger tyres again. For instance, a 535i M Sport has nominal 110mm sidewalls on its standard 18s. Plenty?
How much sidewall is enough?
*Before anyone says "well, buy a spec that has 16" wheels", Mercedes will only sell a very odd, limited model with small wheels, and to spec that up to an equivalent standard as the higher-spec models is financial suicide. Besides, they look pants
I've no idea why Mercedes decided someone who drives a mid-sized saloon should put ultimate grip over the practicalities of carrying people and stuff over the UK's roads. A good quality modern tyre on something like a 16" rim will give you all the grip you can use sensibly on the road, will improve the ride, and prevent the sort of damage you've experienced.
Read the handbook to see what sizes are allowed and buy a set of OE Mercedes rims off eBay. You'll probably find someone will to pay good money for the 18" so it shouldn't cost much to change.
SS7
Read the handbook to see what sizes are allowed and buy a set of OE Mercedes rims off eBay. You'll probably find someone will to pay good money for the 18" so it shouldn't cost much to change.
SS7
loudlashadjuster said:
My thoughts are drifting to a 5 Series/E-Class as they tend to have even larger tyres again. For instance, a 535i M Sport has nominal 110mm sidewalls on its standard 18s. Plenty?
One of my colleagues lives in small village in Bucks and has had a 520d Touring with 18" wheels for a few months. Never mind tyres, he's had 2 wheels replaced due to being buckled in pothole impacts that he didn't think were very severe.shoestring7 said:
I've no idea why Mercedes decided someone who drives a mid-sized saloon should put ultimate grip over the practicalities of carrying people and stuff over the UK's roads. A good quality modern tyre on something like a 16" rim will give you all the grip you can use sensibly on the road, will improve the ride, and prevent the sort of damage you've experienced.
Read the handbook to see what sizes are allowed and buy a set of OE Mercedes rims off eBay. You'll probably find someone will to pay good money for the 18" so it shouldn't cost much to change.
SS7
Yes, had thought about changing wheels wholesale, but it's an expense and a hassle storing the removed wheels (it's a PCP car so has to go back at some point). Think 17s are the smallest supported with the brakes fitted to my car.Read the handbook to see what sizes are allowed and buy a set of OE Mercedes rims off eBay. You'll probably find someone will to pay good money for the 18" so it shouldn't cost much to change.
SS7
I also have no idea why Mercedes, BMW et al think a cooking diesel estate needs such daft tyres, but they're all at it.
Sheepshanks said:
loudlashadjuster said:
My thoughts are drifting to a 5 Series/E-Class as they tend to have even larger tyres again. For instance, a 535i M Sport has nominal 110mm sidewalls on its standard 18s. Plenty?
One of my colleagues lives in small village in Bucks and has had a 520d Touring with 18" wheels for a few months. Never mind tyres, he's had 2 wheels replaced due to being buckled in pothole impacts that he didn't think were very severe.shoestring7 said:
I've no idea why Mercedes decided someone who drives a mid-sized saloon should put ultimate grip over the practicalities of carrying people and stuff over the UK's roads. A good quality modern tyre on something like a 16" rim will give you all the grip you can use sensibly on the road, will improve the ride, and prevent the sort of damage you've experienced.
I'm not so sure - smaller diameter rims will likely use narrower tyres and even with higher profile figures, the side wall height probably wouldn't be much, if any, different.What's needed, as the OP has recognised, is proper SUV tyres - wide AND high profile.
shoestring7 said:
Read the handbook to see what sizes are allowed and buy a set of OE Mercedes rims off eBay. You'll probably find someone will to pay good money for the 18" so it shouldn't cost much to change.
SS7
Probably could only drop to 17" to clear the brake calipers.SS7
Sheepshanks said:
shoestring7 said:
I've no idea why Mercedes decided someone who drives a mid-sized saloon should put ultimate grip over the practicalities of carrying people and stuff over the UK's roads. A good quality modern tyre on something like a 16" rim will give you all the grip you can use sensibly on the road, will improve the ride, and prevent the sort of damage you've experienced.
I'm not so sure - smaller diameter rims will likely use narrower tyres and even with higher profile figures, the side wall height probably wouldn't be much, if any, different.What's needed, as the OP has recognised, is proper SUV tyres - wide AND high profile.
shoestring7 said:
Read the handbook to see what sizes are allowed and buy a set of OE Mercedes rims off eBay. You'll probably find someone will to pay good money for the 18" so it shouldn't cost much to change.
SS7
Probably could only drop to 17" to clear the brake calipers.SS7
A mate has got an Audi A6 diesel family wagon in S Line spec. with 19" wheels. He ends up slaloming along local lanes to avoid the holes, but I agree, the small wheels look silly on the car, juvenile designers and their huge wheel arches are at fault. A set of 15"s with fat 60 profile tyres fill those in my old 911 very nicely. In contrast, Singer use 17"s on their cars and they are cartoonishly large, whereas the same in a 997 look under nourished:
SS7
Edited by shoestring7 on Monday 1st December 13:10
loudlashadjuster said:
The W204 C-Class, in top 'sporty' (i.e. daft*) spec comes with staggered 18" wheels with the following tyres:
225/40R18 = 90mm nominal sidewall height
255/35R18 = 89mm nominal sidewall height
When you consider that Bucks County Council won't even consider filling in a pothole until its depth is almost half of this size of sidewall (40mm minimum, with sharp edges and at least 300mm in size), you can see why this might be a problem.
Note that the sidewall dim that you have calculated is measured from a point in the middle of the wheel; the visible sidewall will be about half of what you've quoted as the total sidewall.225/40R18 = 90mm nominal sidewall height
255/35R18 = 89mm nominal sidewall height
When you consider that Bucks County Council won't even consider filling in a pothole until its depth is almost half of this size of sidewall (40mm minimum, with sharp edges and at least 300mm in size), you can see why this might be a problem.
kambites said:
You might find that fitting wides tyres relative to the rims has more effect than fitting higher profile ones. Modern cars seem to often have slightly "stretched" tyres which exposes the sidewall to damage from potholes more.
I think that this maybe a good call. What's the width of your wheels? How wide a tyre can you fit?My dad has a C-Class 220CDI as his company car, but its only a classic something or other, but the 125 year anniversary model, so upgraded sat nav and media system. It rides on 205 55 16. Which means a nice smooth ride, tyres are under £80 each for a decent brand, although the company sorts this out.
So assuming the Sport has the same size discs, 16 inch wheels will fit.
So assuming the Sport has the same size discs, 16 inch wheels will fit.
Edited by chrislusty on Monday 1st December 15:58
TA14 said:
Note that the sidewall dim that you have calculated is measured from a point in the middle of the wheel; the visible sidewall will be about half of what you've quoted as the total sidewall.
Yes, the sidewall calc is halved, so you can see the problem.This isn't about fixing the current C though, it's more about what I choose next to avoid the same issue. All four tyres are pretty new and I have no intention of buying any more for this one!
Looking around, and subjectively viewing cars with more generous sidewalls, I'm thinking that the anything over 100mm should be a vast improvement and that 110mm is probably the sweetspot, which pretty much means avoiding higher-spec c-segment cars altogether.
Ah, a kindred spirit - I live just across the border in North Oxon.
It's getting beyond a joke - in the last 14 months or so on Mrs BFB's car (9-5 Aero Wagon 225/45 17s) she destroyed 2 rims and 3 tyres (say about 12K miles in total, if that?).
Finally sense has prevailed, the Saab has gone, replaced by an XC70 wearing 215/65 16s. So far, all's well, he says, tempting fate...
It's getting beyond a joke - in the last 14 months or so on Mrs BFB's car (9-5 Aero Wagon 225/45 17s) she destroyed 2 rims and 3 tyres (say about 12K miles in total, if that?).
Finally sense has prevailed, the Saab has gone, replaced by an XC70 wearing 215/65 16s. So far, all's well, he says, tempting fate...
Buckled my wheel with a 45 profile tyre last week on a BMW. It's on 19's and that is pretty much the smalles wheel for my model.
That's the thrid wheel I have done no in 18 months, £670 for a new wheel and the car off the road for a week.
I feel your pain !!
Even the defender with 85 profile tyres has had the steering knocked out by the pot holes !!
Phib
That's the thrid wheel I have done no in 18 months, £670 for a new wheel and the car off the road for a week.
I feel your pain !!
Even the defender with 85 profile tyres has had the steering knocked out by the pot holes !!
Phib
I think this is ever more relevant given the appalling state of our roads. The lower the profile the more your other suspension parts will take a pounding (as well as being increasingly boneshaking). I think 205/55/16 represents quite a good compromise all round, and will likely be the size on my next car.
Drop to 205/55/16? It is a standard size and just clears the sport brake setup.
That said, if you have the AMG-tuned suspension, you may miss the sharpness provided by the larger wheels and tires. I find the car much more enjoyable with the 17" staggered setup (which would also give you more sidewall than the 18s), but to each his own.
That said, if you have the AMG-tuned suspension, you may miss the sharpness provided by the larger wheels and tires. I find the car much more enjoyable with the 17" staggered setup (which would also give you more sidewall than the 18s), but to each his own.
There appears to be a problem with buckled wheels and BMWs even with quite a lot of sidewall. I had 18" on a BMW F10 and one of the alloys had cracks in 9 places.
I'm guessing in normal tyres the sidewall takes some of the force of bumps but with run flats having stiff sidewalls causes the alloy to take more of the force.
I'm guessing in normal tyres the sidewall takes some of the force of bumps but with run flats having stiff sidewalls causes the alloy to take more of the force.
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