Do wheel and tyre sizes affect handling
Discussion
Just read a document that suggests wheel and tyre size have little effect on handling. The article explained that tyre pressure and vehicle weight govern the tyre patch alone, while grip is governed by the coefficient of friction of the rubber alone.
The only benefit of a wider, larger diameter tyre is less heat generation and improved heat dissipation due to less flexing and a longer cooling period. Thus wheel temperature is lower and tyre pressure more stable.
It did suggest that a shorter tyre wall would help prevent the tyre bending.
Would anyone who knows what they are talking about like to differ?
The only benefit of a wider, larger diameter tyre is less heat generation and improved heat dissipation due to less flexing and a longer cooling period. Thus wheel temperature is lower and tyre pressure more stable.
It did suggest that a shorter tyre wall would help prevent the tyre bending.
Would anyone who knows what they are talking about like to differ?
This was discussed on here a while ago. I think lots of articles were linked in to prove the theory that the contact patch was related to vehicle weight and tyre pressure and increasing the width of the tyres only changed the shape of the contact patch. This was about a year ago I think, then everyone went back to saying that they needed fatter tyres for better grip. Not sure whether the theory was disproved or just ignored 
Someone who knows what they're talking about? I've done it so that should be sufficient...
When I went to 275/40 on the rear and 255/35 on the fronts of my old cerbie, and nitrons, valved to joolz's drag spec, the grip was phenomenal! but, I hated corners with them! felt a lot more planted with the 255's up rear and 235s on front.
Craig, who used to own the purple NOS monster, went super wide on the rear, 11 inch wide wheels with some huge tyres, but he went with Ohlins (rich git), and his grip was amazing on the roads, though he had wayyyy too much power for the strip, but I recall him saying the difference in grip was night and day on his cerb, but then he's a proper driver, unlike me who only likes straight lines lol
Hook up is better on fat tyres off the line, but the rear-end snaps a lot, A LOT, quicker and you have no time to correct it in a car with 370+hp weighing absolutely peanuts. Also in the wet, the car felt very very skittish, but the tyres I was using were new SO3's on the rear and F1 GDS3's on the front.
But also, I did notice that on a good hot day, going round bends I had a lot more lateral grip, but it was scary, because I had that much more grip, and then if I was to lose grip for whatever reason, it wasnt a process you could catch, it just happened, spun out a few times.
Bottom line is, my conclusion, I much prefer the cerbera in stock tyre sizes, the overall handling as a package is more readable and well rounded. Unless you're booting down a racetrack all the time or if you got waayyyyyy too many horses (wider tyres reduce wheels spins too), there are more disadvantages than advantages of wider tyres...
Oh and they do look better under those arches (after you grind out!)....
When I went to 275/40 on the rear and 255/35 on the fronts of my old cerbie, and nitrons, valved to joolz's drag spec, the grip was phenomenal! but, I hated corners with them! felt a lot more planted with the 255's up rear and 235s on front.
Craig, who used to own the purple NOS monster, went super wide on the rear, 11 inch wide wheels with some huge tyres, but he went with Ohlins (rich git), and his grip was amazing on the roads, though he had wayyyy too much power for the strip, but I recall him saying the difference in grip was night and day on his cerb, but then he's a proper driver, unlike me who only likes straight lines lol
Hook up is better on fat tyres off the line, but the rear-end snaps a lot, A LOT, quicker and you have no time to correct it in a car with 370+hp weighing absolutely peanuts. Also in the wet, the car felt very very skittish, but the tyres I was using were new SO3's on the rear and F1 GDS3's on the front.
But also, I did notice that on a good hot day, going round bends I had a lot more lateral grip, but it was scary, because I had that much more grip, and then if I was to lose grip for whatever reason, it wasnt a process you could catch, it just happened, spun out a few times.
Bottom line is, my conclusion, I much prefer the cerbera in stock tyre sizes, the overall handling as a package is more readable and well rounded. Unless you're booting down a racetrack all the time or if you got waayyyyyy too many horses (wider tyres reduce wheels spins too), there are more disadvantages than advantages of wider tyres...
Oh and they do look better under those arches (after you grind out!)....
Thanks Pete and Ash
To try and understand difficult things I take them to extremes to imagine what would happen. For example, I imagine if I had tyres one inch wide compared with one yard wide the car would handle differently. Thus, in someway, it must make a difference.
I have 18in rims with 255 rear and 235 front. Looking at my handbook it says the original wheels should be 16in diameter, 235 rear and 225 front.
At present my car feels skittish compared with others I' driven. I'm refurbishing the sustension but was wondering if the wheel tyre combination might also be worth looking at.
To try and understand difficult things I take them to extremes to imagine what would happen. For example, I imagine if I had tyres one inch wide compared with one yard wide the car would handle differently. Thus, in someway, it must make a difference.
I have 18in rims with 255 rear and 235 front. Looking at my handbook it says the original wheels should be 16in diameter, 235 rear and 225 front.
At present my car feels skittish compared with others I' driven. I'm refurbishing the sustension but was wondering if the wheel tyre combination might also be worth looking at.
FeelTheNoise said:
Ignoring the grip issue, I assume the same wheels and tyres in a wider size will increase the unsprung weight and have a negative handling effect in that way? Talking from a semi-ignorant point of view...
Phil
oh yes... Phil
unless you go for some trick racer lightweight wheels to compensate for the heavier tyre... also depends on the make of tyre... some tyres use lightweight structured steel belts and have less overall rubber-weight due to pretty soft lightweight rubber compounds...
Just took a closer look at the handbook.
1) The handwritten document says 4.5GT
2) The engine number says 4200
3) The picture of the engine is a 4.2
4) The specification page says 4.2
The badge on the car says 4.5
The engine looks like a 4.5
The rolling road says 390bhp.
Thus I guess I have a 4.5 engine with a 4.2 handbook and engine number.
Interesting.
1) The handwritten document says 4.5GT
2) The engine number says 4200
3) The picture of the engine is a 4.2
4) The specification page says 4.2
The badge on the car says 4.5
The engine looks like a 4.5
The rolling road says 390bhp.
Thus I guess I have a 4.5 engine with a 4.2 handbook and engine number.
Interesting.
As Brummie says, Tyre brands are the biggest factor, but it's also very Car specific. You read magazine articles where they test and compare different tyre brands, they will come to the conclusion that the overall winner is 'Brand X'. However the tests will have been conducted on (for example) a FWD 150hp VW Golf. So all that test proves is that those 'Brand X' tyres suit a VW Golf best. If you base your tyre decision on that test, and put those same tyres on a 400Hp RWD Cerbera and you will get a very different result.
18" wheels will give a less compliant ride than 17" on a Cerb, but follow the advice of other Cerb owners to decide which tyre brand to go for.
If people just want something that 'looks' good, but handles like s
t, then go for 20" with super wide tyres.
18" wheels will give a less compliant ride than 17" on a Cerb, but follow the advice of other Cerb owners to decide which tyre brand to go for.
If people just want something that 'looks' good, but handles like s
t, then go for 20" with super wide tyres.Mark Hales (always someone to listen closely too if he says something ...) once commented on a discussion he had with Peter Wheeler .. Hales is a bit of a fan of sensible sidewalls and in the conversation Wheeler said that the TVR Tuscan SP6 of that time was designed with 16inch wheels and tall sidewalls in mind but that everyone was demanding 18inch wheels for looks. Hales remarked that people wouldn't be demanding them if TVR didn't offer them on the options list ...
say what you like, style wins over performance 99% of the time for the man in the street. TVR knew this of course.
say what you like, style wins over performance 99% of the time for the man in the street. TVR knew this of course.
spitfire4v8 said:
Mark Hales (always someone to listen closely too if he says something ...) once commented on a discussion he had with Peter Wheeler .. Hales is a bit of a fan of sensible sidewalls and in the conversation Wheeler said that the TVR Tuscan SP6 of that time was designed with 16inch wheels and tall sidewalls in mind but that everyone was demanding 18inch wheels for looks. Hales remarked that people wouldn't be demanding them if TVR didn't offer them on the options list ...
but they only put them on the options list because they were fed up with the aftermarket boys taking a large chunk of the profit on a sale...not sure I follow that one, how many aftermarket wheels do you see on TVRs ? not many. And this was an interview in about 2001 when there wasn't the likes of SP or ACT doing their wheels. TVR spotted a market yes, but it wasn't one heavily populated by the aftermarket suppliers, that came later.
spitfire4v8 said:
not sure I follow that one, how many aftermarket wheels do you see on TVRs ? not many. And this was an interview in about 2001 when there wasn't the likes of SP or ACT doing their wheels. TVR spotted a market yes, but it wasn't one heavily populated by the aftermarket suppliers, that came later.
2001 sounds about right. Maybe not many TVRs with aftermarket wheels but enought to concern PRW.Gassing Station | Cerbera | Top of Page | What's New | My Stuff