Discussion
One question I have which David Hendry wasn't able to awnser.
Are you able to increase the size of the alloys/rolling radius without any problems? When I get my Griff, I'd like it to look a little different so would think of whopping larger alloys on, something like 17's front and back.
Opinions/Problems etc?
Are you able to increase the size of the alloys/rolling radius without any problems? When I get my Griff, I'd like it to look a little different so would think of whopping larger alloys on, something like 17's front and back.
Opinions/Problems etc?
If looks are your main interest then carry on. However, I am not a chassis engineer but I do know that ever wider, lower profile tyres do not usually do anything but harm to steer feel, stability on rutted roads and probably lots of other things. I don't know anything about Griffith but the one TVR I have driven (a 1999 Chimaera) was frightenlingly bad to drive (see my profile for basis of this opinion!) without putting it on the wrong tyres.
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I don't know anything about Griffith but the one TVR I have driven (a 1999 Chimaera) was frightenlingly bad to drive (see my profile for basis of this opinion!) without putting it on the wrong tyres.
Perhaps you're just not suited to proper sports cars Joe, stick with Suzukis and the like which isolate you better from the TVR type of drive.
As to 'wrong tyres' I don't think anyones mentioned that. If Griffith owners fit larger wheels the correct tyres would be fitted, usually of a profile to keep the rolling radius the same. The lower sidewall will offer less flex than the original and make the ride firmer - that may be what some people want.
As I'm sure you know from your extensive experience many manufacturers offer larger wheels as an option, including MINI and TVR.
JSG.
JSG is quite right, manufacturers do offer larger wheels and tyres but it is because their customers prioritise looks over function. I know for a fact that BMW chassis engineers think their cars (saloons and Mini) are better on the smaller higher profile tyres.
Reduced sidewall flex is actually the problem if it is taken too far (I am not advocating a return to 100 section cross plies!), it causes the tracking along ruts and harsh ride that make for a worse sports car. Don't fall for the stiff+harsh=good theory, Colin Chapman didn't and I am happy to follow his technical lead.
If you really think the Chimaera drives well then there is nothing I can say. Instability, poor pedal layout and over heavy steering are not good things to some of us. TVRs look and sound fantastic but they are far from perfect. As a driver's car, the Chimaera did not touch the Elan, Excel or Esprit.
Reduced sidewall flex is actually the problem if it is taken too far (I am not advocating a return to 100 section cross plies!), it causes the tracking along ruts and harsh ride that make for a worse sports car. Don't fall for the stiff+harsh=good theory, Colin Chapman didn't and I am happy to follow his technical lead.
If you really think the Chimaera drives well then there is nothing I can say. Instability, poor pedal layout and over heavy steering are not good things to some of us. TVRs look and sound fantastic but they are far from perfect. As a driver's car, the Chimaera did not touch the Elan, Excel or Esprit.
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I know for a fact that BMW chassis engineers think their cars (saloons and Mini) are better on the smaller higher profile tyres.
"Better" is subjective though. There's always a compromise.
I want my car to handle well on track and I'm happy to compromise its road manners slightly to achieve this. Others want their cars to look distinctive and again they're willing to compromise other areas to do it. Their choice.
There does seem to be a fashion to get bigger and bigger wheels, heading towards the rubber band concept car type of look. Not to my taste but for some people looks are more important than handling etc so fair enough.
Re your views on stability, pedal layout, steering weight etc - I haven't had any problems, but then I'm not you. Wouldn't it be boring if we all agreed about everything?
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I would like larger wheels on my Griff .. not realy just for cosmetics, I would like to leave the front the same width, but go wider on the back if poss to get more traction on accelerating and cornering.
Has anyone increased the rear footprint and had any probs?
The current cars are 245 at the back and there really isn't much clearance available to go much wider and retain the same rolling circumference. If you are running 225s then this is a easy change and involves no wheel change. Beyond that you probably be abl;e to squeeze a 255 in but with a bigger diameter wheel and lower profile tyre which reduces the sidewall flex and can make the ride harsher which means over rough surfaces you can actually loose traction.
Life with tyre and suspension change sis always a compromise.
Steve
Yes and no.
Most manufactuers will list a min and max wheel width for their tyres. They can and do vary and then you get people like me who take a tyre and deliberately fit it to a wider wheel than recommended to brace the side walls so that they are stiffer without having run higher pressures.
The profile is also adds to the problem because the wheel width can determine the tyre contact patch and any problems can vary with the profile.
Steve
Most manufactuers will list a min and max wheel width for their tyres. They can and do vary and then you get people like me who take a tyre and deliberately fit it to a wider wheel than recommended to brace the side walls so that they are stiffer without having run higher pressures.
The profile is also adds to the problem because the wheel width can determine the tyre contact patch and any problems can vary with the profile.
Steve
As a rule of thumb, I think the tyre width should be the rim width plus about an inch. But, as Steve says, this does vary from tyre to tyre. The problem is different types have different amounts of flex which affects the relationship between the nominal width, and the size of the contact patch.
As an example, I was running the conventional 245/45 S02pp on 16x7.5" rims for a while. The contact patch width was only about 190mm. This was actually only about 10mm wider than the 205/55 tyres I had on the front.
I suspect what was happening was the S02 sidewall had so much flex that the tyre bulged more than normal producing misleading nominal widths. Looking at the shape of the tyres, the fronts were a far better fit on the rims and in fact the rears were quite distorted, although the wide rubbing strips hid this.
The S03s I have on now are only 225 section but have a wider contact patch than the S02 "245", and they fit the rims far better.
As an example, I was running the conventional 245/45 S02pp on 16x7.5" rims for a while. The contact patch width was only about 190mm. This was actually only about 10mm wider than the 205/55 tyres I had on the front.
I suspect what was happening was the S02 sidewall had so much flex that the tyre bulged more than normal producing misleading nominal widths. Looking at the shape of the tyres, the fronts were a far better fit on the rims and in fact the rears were quite distorted, although the wide rubbing strips hid this.
The S03s I have on now are only 225 section but have a wider contact patch than the S02 "245", and they fit the rims far better.
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