Wider tyres or not
- Thread starter kerstien
- Start date
CornishRob
Senior member
I think mmmfive has run the wider tyres as well as OEM size. I'm sure he will be along at some stage to suitably advise on each tyres pros/cons.
I think supply was an issue for PSS tyres, but think its possible to get in OEM size now.
I think supply was an issue for PSS tyres, but think its possible to get in OEM size now.
Liverpool
I have 235 wide AD08s on my front but stock width rears (Couldn't find 225's when i needed to buy). Just 1 size up will be totally fine but difference in performancewill not be much really.
AD08s and i'm sure AD08Rs already run wider than equivalent sized tires, if your only option is 235 and 265 then it's OK, but stock should be practically the same performance and a bit cheaper to boot.
Happy to be corrected if you think i'm wrong though.
AD08s and i'm sure AD08Rs already run wider than equivalent sized tires, if your only option is 235 and 265 then it's OK, but stock should be practically the same performance and a bit cheaper to boot.
Happy to be corrected if you think i'm wrong though.
kerstien said:
Here's a decent summary from here: http://www.physicsforums.com
Mehcanisms of Tire grip.
Friction
Mechanical Keying
Adhesion
As they are made from deformable rubber, tires dont exactly follow basic friction theory. So to just say that F=mu*r is strictly wrong. Although it basically does floow this during the elastic range.
Tires only give grip when they are at the correct temperature. this is the most important thing you can remember about tires .
Now on to business.
Tires are the most important part of the suspension, either they are designed to fit it, or the suspension is designed around the tire.
People who say wider tires make more grip because ;''there is more rubber on the road' are wrong. They are both wrong that it makes mroe grip and that there is more rubber on the road.
When you make a tire wider, you alter the contact patch to be wider , but it reduces in length. So depending on sidewall stiffness, a wider tire can actually give less rubber on the road.
The main reason for tires being the size they are is actually heat management. Wider, low sidewall tires will cool better than narrow tall tires. If you can;'t get a tire up to temperatie it will give no grip, if you get it too high you will cook the rubber and ruin the set of tires.
Back to contact patch, you can safely assume that contact patch stays roughly the same area with wide or narrow tires (as long as the load stsys the same). Narroe will have longer contact patches and wide tires will have shorter.
The reason why F1 tires are wide is primarily so that they dont cook (remember they arent just wide, they are fairly high sidewalled), but they ten dto have wider contact patches because they will give better grip going round corners.
A wide tire will generate more lateral force per slip angle making cornering better. F1 cars DO NOT have wide tires for linear acceleration.
Conversely (Mike im goin to have to disagree with you here) drag racers acutally use the tires not becuase of the width, but the tallness. As we know a wider contact patch gives better cornering performance, a narrow but long contact patch is what you want for linear acceleration.
so strangely, drag racers will actually be better with narrow tires. So why do they use wide tires? (remember the most important gip aspect of tires) Temperature! They want as longer contact patch as they can get, but need the width for cooling. (eith 4000+ horsepower you do kind of build temp rather well)
But if you look at the contact patch shape between say, an F1 car or drag racer. (both are considered to use wide tires). The F1 patch will be wider and shorter for good cornering, the drag patch will be longer and narrower (relatively) for good linear acceleration.
So to sum up: Wider tires are not always better. They dont always give better traction. It depends on the car, the situation, the conditions.
Eg. Rally cars use wider tires when on tarmac rallys, and use (surprisingly) very thin tires on ice rallys.
F1 cars used to use narrow tires until aero began to be used in the 60's.
Drag racers acutally want tall tires, width is there to stop the tire being destroyed.
TEMPERATURE!!!!!! rawr.
As example I can think of is formula student cars, they used to use 8inch tires but couldnt get them up to temperature. They switched to 6.5inch and got more grip because they can get them up to temp.
To this I would add that the shape of the contact patch will also be very much a result of being able to limit lateral body roll during cornering. If your tyres wear out the inside/outside edges fastest, then as I see it, all the theory of tyre contact patches goes out of the window, and this is the reason that I like to sort out the suspension so that the dynamic geometry keeps the contact patch across the full width of the tyres. Unless you sort out the suspension/geometry, then running wider tyres is a waste and they will just cost you more.
Exodus - great explanatory post to dispel many of the myths people have about tyres.
It's for most people just a cosmetic change rather than requirement or even useful.
Sent from my iPad using Tapatalk HD
It's for most people just a cosmetic change rather than requirement or even useful.
Sent from my iPad using Tapatalk HD
Excellent reading as always exdos
re dragsters, I always thought that the combined low pressures and hieght/width of tyres and soft compund was a basic form of traction control (on slow mo's you can see the hubs twisting the sidewalls, almost dragging the contact strip round), the power those things throw out, if they were normal pressured low profile wide tyres, they'd just be spinning at standstill until the fuel ran out...
re dragsters, I always thought that the combined low pressures and hieght/width of tyres and soft compund was a basic form of traction control (on slow mo's you can see the hubs twisting the sidewalls, almost dragging the contact strip round), the power those things throw out, if they were normal pressured low profile wide tyres, they'd just be spinning at standstill until the fuel ran out...
The warmest that I've ever got the rear tyres of my Z3MC with spirited driving on the road is 58 degs C, but with the same tyres (Falken 452s) at The Ring, I've had them at 80 degs C in similar ambient temperatures, because I've been able to properly use the tyres' slip angle on track.kerstien said:Since most of my journeys are rather short I think I should stay with oem then for performance as they will probably not heat upKerstien
kerstien said:
Most cars have a square set up, but presumably the Z4M has wider tyres to cope with the increased heat produced by putting 338hp through them for traction, whereas the fronts don't usually get as hot as the rears. Because the Z4M has wider rear tyres, it consequently has a wider rear track width than the front and using a square set up of the same wheel/tyres sizes F&R will reduce the difference in track widths. Some people suggest that this tends to reduce a tendency to understeer and I think that's the primary reason for using a square set up with the secondary benefit of being able to rotate tyres all round.
I've never tried a square set up with the Z3/Z4 MCs but I have tried using spacers on the fronts only, to reduce the difference in track width, but I didn't like the handling: it made the handling seem a bit "numb". Perhaps this was due to the fact that I'd already got the cars handling neutrally with the suspension and geometry changes that I'd made.
Sae said:Excellent reading as always exdos
re dragsters, I always thought that the combined low pressures and hieght/width of tyres and soft compund was a basic form of traction control (on slow mo's you can see the hubs twisting the sidewalls, almost dragging the contact strip round), the power those things throw out, if they were normal pressured low profile wide tyres, they'd just be spinning at standstill until the fuel ran out...
I know nothing about dragsters, but when you see all that "slack" in the rubber in slo-mo, it looks to me as though its acting like a spring loading to prevent excessive wheelspin, for the take off as you suggest. The low pressure also allows the rapid increase in heat created during the run to expand the air inside without increasing pressure too much that would make the tyre too rigid at that end with ballooning distortion of the contact patch.
exdos said:The warmest that I've ever got the rear tyres of my Z3MC with spirited driving on the road is 58 degs C, but with the same tyres (Falken 452s) at The Ring, I've had them at 80 degs C in similar ambient temperatures, because I've been able to properly use the tyres' slip angle on track.kerstien said:Since most of my journeys are rather short I think I should stay with oem then for performance as they will probably not heat up
kerstien said:
Most cars have a square set up, but presumably the Z4M has wider tyres to cope with the increased heat produced by putting 338hp through them for traction, whereas the fronts don't usually get as hot as the rears. Because the Z4M has wider rear tyres, it consequently has a wider rear track width than the front and using a square set up of the same wheel/tyres sizes F&R will reduce the difference in track widths. Some people suggest that this tends to reduce a tendency to understeer and I think that's the primary reason for using a square set up with the secondary benefit of being able to rotate tyres all round.
I've never tried a square set up with the Z3/Z4 MCs but I have tried using spacers on the fronts only, to reduce the difference in track width, but I didn't like the handling: it made the handling seem a bit "numb". Perhaps this was due to the fact that I'd already got the cars handling neutrally with the suspension and geometry changes that I'd made.
Perfect tanks for the explanation John. I'm still playing with the settings on them v3s and so far I'm impressed. Next is balancing and alignment