Wide Tires

[Xrb]

I tried searching but didn't find the info I wanted. Im about to buy new wheels/rims (neuspeed rse10) but Im deciding between 18x8 with 245/40r18 or 18x8.5 with 255/35r18. Im on stock suspension.

Anybody with experience on this tire sizes? Im particularly interested in knowing if I can run 255s on stock hight n suspension without rubbing issues, the 245 would be the safe bet. Antbody running 255?

Thanks

 

[Damo H]

I tried searching but didn't find the info I wanted. Im about to buy new wheels/rims (neuspeed rse10) but Im deciding between 18x8 with 245/40r18 or 18x8.5 with 255/35r18. Im on stock suspension.

Anybody with experience on this tire sizes? Im particularly interested in knowing if I can run 255s on stock hight n suspension without rubbing issues, the 245 would be the safe bet. Antbody running 255?

Thanks

Not a popular tyre size, but you can do some quick calculations if you know the wheel offset to work out how much closer things will get. Then you can compare with other people’s setups with higher offset wheels and or spacers to get a good idea of any issues.

 

[Xrb]

Not a popular tyre size, but you can do some quick calculations if you know the wheel offset to work out how much closer things will get. Then you can compare with other people’s setups with higher offset wheels and or spacers to get a good idea of any issues.

Oh yes, the wheel offset is 45 in both cases

 

[Damo H]

Oh yes, the wheel offset is 45 in both cases

So that’s 5mm closer to the outer arch just with wheel and in theory an additional 10mm closer with the tyre not taking into account how tall the tyre is and different spec etc.
So for outer edge 15mm spacer. Think most people only run 10 at front. But 15 Rear is fine.

Inner edge again using the basics it’ll be 5mm closer to the inner side.

Better getting exact tyre specs to compare 100%

Why 255, potentially it’ll handle worse.

 

[Matt]

So that’s 5mm closer to the outer arch just with wheel and in theory an additional 10mm closer with the tyre not taking into account how tall the tyre is and different spec etc.
So for outer edge 15mm spacer. Think most people only run 10 at front. But 15 Rear is fine.

Inner edge again using the basics it’ll be 5mm closer to the inner side.

Better getting exact tyre specs to compare 100%

Why 255, potentially it’ll handle worse.

Why do you think it may handle worse?

 

[Mr Pig]

Why do you think it may handle worse?

Interested in this answer too.

 

[Damo H]

Why do you think it may handle worse?

With tyres it’s not always as simple as wider is better. You have to consider the balance and feel of the car, not to mention traction in wet vs dry.

Sometimes a wider tyre may offer more technical grip but less feel and predictability, therefore less confidence and slow you down.

Then there is weight, typically a wider tyre will be heavier and the weight is where you want it least, as unsprung and rotational mass. I can’t remember the exact details, but 1kg of unsprung rotational mass is worth something like 4kg of sprung mass. The suspension has to deal with it, the engine has to turn it, and the brakes stop it.

Another factor is that although 2 tyres might be 235/35 R19 on the side wall, they won’t have the same specs but will be within a criteria. This difference maybe bigger still when considering such a big jump.

I’m not saying it will handle worse, but there is no guarantee it will handle or feel better.

This video here is good for giving you an idea. In this case wider is better in the dry, but this guy explains it better than me of why it’s not always a case of wider is better.

 

[Matt]

Thanks

 

[cupra14]

Any greater unsprung mass is definitely unwanted for performance and handling - and will inevitably cause faster wear on suspension-related parts.

That does not necessarily mean you shouldn't fit them - you are free to choose of course.

In the UK and many other places, tell your insurer.

 

[Mr Pig]

Sometimes a wider tyre may offer more technical grip but less feel and predictability, therefore less confidence and slow you down.

That may be generally true surely only if all else is equal? For example, wider tyres often also have a lower profile which will offset any loss of feel?

 

[Damo H]

That may be generally true surely only if all else is equal? For example, wider tyres often also have a lower profile which will offset any loss of feel?

Lower profile does not necessarily give better feel, F1 cars have massive sidewalks but they don’t have an issue with feel.

Thinner side walls will need to be stronger, thicker etc, so that means they are more likely to cause more reaction in the suspension. If you’re on track, then in theory it maybe better. But if that’s the case why are people from my old MINI world tracking their cars on 17’s rather than 18”s or even 19’s.

There is a balance to be had. And without trying it and testing it you’ll probably never know. But I stand by my original comment, wider tyres doesn’t necessarily give you a better handling car.

 

[Mr Pig]

F1 cars have massive sidewalks but they don’t have an issue with feel.

But they have bugger all suspension! As I was saying, it's all relative.

 

[Damo H]

But they have bugger all suspension! As I was saying, it's all relative.

Exactly so fitting wider tyres won’t always make your car handle better. Otherwise we’d all be running 380 wide tyres with no profile.

 

[LouG]

Wider tyres can mean higher G forces before they let go. The breakaway point then is often more sudden and deters the driver from approaching that point. So, effectively, you have less grip that you are willing to explore.
Bikers all know this very well. A predictable tyre is much more confidence inspiring than a sticky, snappy one.

 

[Oldbutswift]

The other thing is that if you are getting into fine detail about handling (not grip) you need to be aware of tyre width versus rim width.

For any tyre width there are usually 3 possible/recommended rim widths and the widest is said to promote the best handling because it supports the tyre walls better so the tyre doesn't move around as much under load.

So it is not always a good idea to go for a wider tyre on the same rim.

(I am not talking about the situation where a narrow tyre is put on a really wide rim to give that stupid and potentially dangerous "stretched" look!)

 

[Damo H]

The other thing is that if you are getting into fine detail about handling (not grip) you need to be aware of tyre width versus rim width.

For any tyre width there are usually 3 possible/recommended rim widths and the widest is said to promote the best handling because it supports the tyre walls better so the tyre doesn't move around as much under load.

So it is not always a good idea to go for a wider tyre on the same rim.

(I am not talking about the situation where a narrow tyre is put on a really wide rim to give that stupid and potentially dangerous "stretched" look!)

Do not get me started on the ‘stretched’ look.

I appreciate everyone has different wants and tastes. But stretched look is just wrong.

 

[Xrb]

Do not get me started on the ‘stretched’ look.

I appreciate everyone has different wants and tastes. But stretched look is just wrong.

The streched look just screams poseur, it’s ridiculous, also the extreme camber

 

[Xrb]

Reasonably wide tires are sexy, but like some of you are saying the most important thing is balance. I think the 225 that come with my car are also compromising between balance n cost. The record setting cupra was sporting 235 if I remember correctly.

Also, I was just looking into REAL tire tread width, Tire Rack measures each tire with their own and same tool, and list the results, some 225 tires have a wider tread then some 255s, thats creazy and makes the numbers practically useless.. that is because the industry has very generous tolerances for the number manufacturers place on their tires, so each manufacturer varies.

Its complicated and its a matter of experimenting to find what you want, some drivers might enjoy wider tires caracteristics and other might prefer other setups. This also changes with tire models, some are stiffer and offer different characteristics even for the same size... And all this without getting into compounds...

Dont sweat it, try things and find what you like. Just do it for the drive and not the pose

 

[Damo H]

Reasonably wide tires are sexy, but like some of you are saying the most important thing is balance. I think the 225 that come with my car are also compromising between balance n cost. The record setting cupra was sporting 235 if I remember correctly.

Also, I was just looking into REAL tire tread width, Tire Rack measures each tire with their own and same tool, and list the results, some 225 tires have a wider tread then some 255s, thats creazy and makes the numbers practically useless.. that is because the industry has very generous tolerances for the number manufacturers place on their tires, so each manufacturer varies.

Its complicated and its a matter of experimenting to find what you want, some drivers might enjoy wider tires caracteristics and other might prefer other setups. This also changes with tire models, some are stiffer and offer different characteristics even for the same size... And all this without getting into compounds...

Dont sweat it, try things and find what you like. Just do it for the drive and not the pose

Agree with what your saying, but did you mean some 225 are wider than 235? That I can believe, but no way a 225 would be wider than 255.

 

[LouG]

Tyre width is the actual width at the widest point, not tread width. They can be quite different on some tyre designs.