Tyre width question

[croyde]

Hello All

A mate of mine has just called and asked me if he can replace the worn 245 tyres on his 9 year old S-Class with some bargain 255 tyres that he has seen on eBay.

Is this possible or completely dependent on his rim size?

Cheers.

[markbe]

croyde said:

Hello All

A mate of mine has just called and asked me if he can replace the worn 245 tyres on his 9 year old S-Class with some bargain 255 tyres that he has seen on eBay.

Is this possible or completely dependent on his rim size?

Cheers.

So long as the Aspect ratio is the same it should be no problem.
Ie; 245.45.17 to 255.45.17.

Mark.

[croyde]

Cheers and it is the same aspect ratio. Ta.

[yellowbentines]

should be ok, I went the other way from 255 to 245 with no problems.

[V8Maverick]

markbe said:

croyde said:

Hello All

A mate of mine has just called and asked me if he can replace the worn 245 tyres on his 9 year old S-Class with some bargain 255 tyres that he has seen on eBay.

Is this possible or completely dependent on his rim size?

Cheers.

So long as the Aspect ratio is the same it should be no problem.
Ie; 245.45.17 to 255.45.17.

Mark.

Eeek, I don't like to contradict here, but that's the wrong answer.
Conversion is all about overall diameter, not aspect. In this instance the 255 is only just outside of recommended tolerences (though it is still outside and as such your speedo and odometer will be slightly wrong), but I had to point this out as saying "as long as the aspect is the same then it's fine" as general advice could end up with people thinking they can convert from 205 or 215/45R17 to 255/45R17 or higher with no probs, when in fact the difference in size is 6 or 7 % and will cause massive issues in handling, potential diff problems and the obvious fact that all of the instruments will read wrongly.

Besides - Why buy tyres from ebay when you'll still have to pay a garage to fit, valve and balance, which could cost as much as £25 a tyre. You don't know their history and indeed why they're being sold there rather than from a reputable garage (have they had a major puncture repair? Are they out of shape? Cuts / Bulges?) not to mention that cheap tyres, in last weeks autocar tests pulled up over 60feet longer than premium in the wet @ 70mph. Is it worth your car / insurance / life to save a few quid?

That's all

[croyde]

Personally I would never buy secondhand tyres and go into a lot of research to buy what's best for my Beemer, Triumph, Giant or Specialized but my friend always likes to go for a bargain.

Maybe that's why he can take the family on 4 exotic holidays a year whilst all I can manage is a rainy weekend in Center Parcs.

[boyzee]

Just as a word of warning on second hand tyre,s,I bought a secondhand rear tyre for my E55.The tyre was like brand new and a lot cheaper than a new one.I was well pleased with my purchase but after a few weeks my car had a bad vibration above 80 mph,below this speed it was fine.I had the prop uj,s replaced but still this problem existed.I tried everything to solve this then i changed the tyre and the car is now fine.Looking at the tyre i bought there are no tell tale signs anything is wrong with it but maybe it came off of a damaged car or something.I would only buy new after this.

[Dog Star]

boyzee said:

I would only buy new after this.

Do you change all the tyres straight away if you buy a used car? (Assuming like me that you are one of the great unwashed that buys used cars )

[boyzee]

Dog Star said:

boyzee said:

I would only buy new after this.

Do you change all the tyres straight away if you buy a used car? (Assuming like me that you are one of the great unwashed that buys used cars )

Dog Star i am only stateing what happened to me with the tyre i bought.I am unemployed and had to get the cheapest tyre i could at the time so i paid £80 for what i thought was a bargain.This tyre ended up costing me a lot more trying to solve the problems it caused to my car.Of cause i don,t buy new tyres when i buy a second hand car,only when they need replaceing.I have never had a brand new car,im just trying to put my point across regarding secondhand tyres that may have come off of a damaged car and may be faulty.

[steve-V8s]

First of all you need to know what width the rims are, then find out from the tyre manufacturer what the allowable width rims are for that particular tyre. Better tyre companies have the possible rim fitments on their web sites. If the tyres will actually fit ( or will be safe to fit) on the rims you now need to calculate the difference in rolling diameter. There are a number of converters on the web that allow you to input two tyre sizes and report the diameter difference. Next you need to consider if there is adequate clearance within the wheel arches for the wider rubber. If all that is OK then check the speed rating is correct for the car. Oh and if they are not a standard fitment for the car he will have to tell his insurers.