Rough roads - what difference would these wheel/tyre sizes make?

[DIYNotIan]

Hi

I'm looking for a new (used) car. Needs to tick several boxes, one of which is that I live in the mountains where the roads are poor quality with loads of rough patches, potholes, etc.

The cars I've short listed have the following spec tyres:

- 205/55 R16.
- 205/60 R16.
- 215/65 R16.

I've been told that the higher the side wall of a tyre, the more it will protect the suspension of the car and save frequent trips to the garage for new drop links, bushes, shocks, etc. I seem to have to have these sorts of things changed a lot at the moment!

With that in mind, how much difference would the above size wheels/tyres make?

Also. is it possible to easily change a car's tyre size, say from 205/55 R16 to 215/65 R16? Or would that be a real pain both practically and when it comes to insurance etc?

Many thanks

 

[robinbanks]

I've been told that the higher the side wall of a tyre, the more it will protect the suspension of the car and save frequent trips to the garage for new drop links, bushes, shocks, etc. I seem to have to have these sorts of things changed a lot at the moment!

Yes, it's a reasonable assertion. You could also be taking your cars to be MOTed by someone a little bit overzealous with the pry bar though.. Maybe get a second opinion if you're paying for new suspension parts every year


Regards changing your wheels and tyres, you can't fit different sized tyres to the same rims without affecting the circumference of the tyre, which will have an effect on the indicated speed on the dash. If you make an adjustment that means the speedo reads more than 10% over true, or it reads any amount lower than true, it's illegal.

If you want tyres with higher sidewalls you'll need to reduce the rim size accordingly so that the overall radius of the wheel is maintained. Fitting different size tyres to those in the range of sizes specified by the manufacturer may be deemed a modification by your insurer; you should notify them of the change, even if the new tyre is the same circumference as the old, as higher sidewalls means that there is more deformation in the tyres when cornering

 

[DIYNotIan]

Many thanks for the reply and explanations.

That makes sense RE reducing the rim and increasing the side wall to maintain the overall same radius. I tend to drive quite slowly and carefully nowadays, not like I did when I was younger! So I'm not so worried about performance as such.

I guess ultimately I'll need to look into it further as to how much difference it actually makes, and how much more protection say a Dacia Logan Stepway with 205/55 R16 tyres would compare to a Duster with 215/65 R16. And by that token how the two cars would compare if the Logan would compare if reduced to R15 and higher sidewall tyres accordingly.

Or whether I'm completely overthinking it all!

Thanks again

 

[yorksbuilder]

where the roads are poor quality with loads of rough patches, potholes, etc.

You mean anywhere in the UK?

 

[JohnD]

I have a car that can use 20" wheels with 30 profile tyres
Or 18" wheels with 50 profile tyres (my winter wheels)
Or 19" with something else
All these variations give the same rolling circumference. Bigger tyres on a smaller wheel and vice versa.

The 20" low profile are supposed to look more flashy and drive racier

They are also a bumpier ride and prone to buckle on projecting draincovers and other projections

For what you describe, get the little wheels and big tyres. There will be a limit to clear your brakes.

Your handbook will tell you what you can have, and it may also be on the filler cap label.

You may be in a country that requires winter tyres.

For economy you can often get good wheels from a scrapyard.

Note that the nuts for alloy wheels are a different shape and must not be used on steel wheels (except sometimes if you have a matching spacesaver)

 

[Harry Bloomfield]

- 205/55 R16.
- 205/60 R16.
- 215/65 R16.

The lower that second set of numbers, the lower the profile - the greater the amount of direct tyre noise transferred into the body, and the cab, but the more 'planted' will be the car, on the road. It will also feel harsher, on a rough road. The higher the first number, the wider the tyre tread, the more grip it provides with the road.

 

[JohnD]

.

 

[Avocet]

Everyone has already mentioned about the tyre profiles. However, I'm not sure that it's going to make an appreciable difference to the life of the suspension components you mention. The larger second number puts more tyre sidewall between the wheel rim and the tarmac (and protects the rim itself from damage much better), but if the suspension moves, there will still be wear and tear on droplinks and bushes. Obviously Dacias are cheap cars and there are reasons for that. A more expensive car might use better quality suspension components that will last longer, but it might be cheaper to just replace the suspension parts more often!

Another thing, is that if you are replacing suspension parts, there is a mountain of cheap, "no-name" Chinese tat on the market and in general terms, a £9.99 droplink is probably going to be made of fudge. When replacing, go for recognised, branded parts like TRW, or Delphi (or genuine manufacturer's ones, of course).