215/50/15

[Limbo]

hey guys any of you with eks running the profile 215/50/15?
Just wondering if they will fit without rubbing.
I've currently got 205/55/15 they seem fine but i need wider tread for more traction.

[[ricer]]

i think im running 215 45 r16
no rubbing

[fatboyz39]

why not run R compund tyres? that'll stop traction issue.

[Limbo]

ricer - now you tell me. I wanna come by and have a lookie

fatboy - i wanna be able to stop in wet. I've heard some bad stories from friends running semis in wet

[[ricer]]

yeah i had kumho semi in wet = the gay
but in the dry its MAD

just get really good street tyres in the right profile limbo and if u wanna run just take out alot of pressure
but i reckon no matter what... ur huge fwd power is gonna spin tyres still lol

[vinnY]

i got 205/50/15 at the rear and it appears fine, haven't tried up front though

[55EXX]

i have 215/45/15 toyo's and they are the best tyres i've ever had! you will find 215/50 will give you too big of a rolling diameter. need to go 45 profile. this on a eg with super lows no srcubbing.

[Limbo]

Vinny - mate they are smaller than what i currently have on front.

55exx - cool, i'll look into the 215/45/15, u sure 215/50/15 is too big? cos they said 205/55/15 were too big also. I need a chuncky tyre anywayz dun want them too low profile. How much did you end up getting urs for? WHere did you get them from cos i can't seem to find out where they have them

Ricer - i want some fuel economy also you know i dun wanna be like some people driving around with 28PSI LOL

[Limbo]

alrightly some more info i found out.

The rolling diameter of the following
195/55/15 (Stock rolling diameter) = 23.44" @ 100km
215/50/15 = 23.46" @ 100.1km/hr
205/55/15 = 23.88" @ 101.8km/hr
225/50/15 = 23.86" @ 101.8km/hr
215/45/15 = 22.62" @ 96.5km/hr

i got this excel tire selector i found off the net that works out diameters! Pretty cool stuff

anyone know where i can get 215/50/15???

[SeverAMV]

the only thing that affects traction with a tyre is the compound, not the width. fitting wider tyres dont give a bigger contact patch, they just deform the contact patch and make it wider, which makes it more stable in a straight line, it doesnt give it more grip. so if you're going wider, change to tyres that have a softer compound, as wider tyres help in cooling so it balances out.

[Limbo]

mate are you nuts, of cos a wider tyre is gonna give better grip.

If you get the same tyre with different widths i'm sure you will notice the traction difference. Otherwise why would drag cars have such massively wide tyres?

[vinnY]

http://www.carbibles.com/tyre_bible_pg2.html
read the 'Fat or thin? The question of contact patches and grip."

so it appears severamv isn't nuts

[SeverAMV]

mate are you nuts, of cos a wider tyre is gonna give better grip.

If you get the same tyre with different widths i'm sure you will notice the traction difference. Otherwise why would drag cars have such massively wide tyres?

dude, drag tyres are made from very soft compound in order to increase grip, the compound is different to street tyres which is why they have more grip. reason why they have wider tyres is to aid in cooling the tyre to maximise the amount of grip available and to increase the longevity of the tyres. a wider contact patch (deformed) will not give you more grip, it will just be more stable because the contact patch is wider. the traction difference as you call it is only noticeable with different widths of the same tyre at their individual limit, as the wider tyre will have better cooling and hence more useable grip for a longer duration than the skinner tyre. thats the only difference if they use the same compound.

[Limbo]

i understnad what vinny is talking about but, the patch is still gonna be bigger on a wider tread if you deflate it to the same PSI. That's why you run at 28PSI for drags.

Your saying that 'usable grip' is dependant on cooling on tyre width?
I don't think the cooling effect would be that noticable on a 12s 1/4. And even less on cars that make 9s passes. That's why some drag cars don't even bother with the intercooler cos the short burst is too quick to cool a car down.


If the contact is bigger than there is more surface area available for grip.

[Limbo]

Also tyres are designed to operate at a certain heat range, i'm sure R&D look into the amount of heat dissapation the tyre will take or need.

[SeverAMV]

as i've mentioned, contact patch doesnt affect dry traction. contact patch only has an effect on wet traction.

and you'd be suprised how much an effect cooling can have on quarter mile drags, remember how you are recommended to do a burnout before you make the run? if your tyres have poor cooling effect, you'll melt your tyres before you even make the run. good wide tyres should be able to remain at their ideal working temperature, which is why they have better grip.

and the people who dont use an intercooler on drags dont do it because they dont need its cooling functions, they do it for slightly better response.

R&D do look into the amount of heat dissipation the tyre will need, but there are legalities that restrict the type of compound that can be used on the street, as well as the width of the tyre you can fit under your guards, plus they accommodate for the occasional sporting outing that people take their cars on, they dont accommodate for cars thrashed on the hills non-stop for half an hour. there are far more factors than you're thinking of.

[beeza]

I was qouted $196 for Toyo Tr1's fitted and balanced.Does anyone know if U can get them much cheaper?

[Limbo]

mate you do burnouts to get tyres to the right temp to grip properly so that the compound is at operating temp. Doesn't mean that it makes for better cooling.

Trust me contact patch does make alot of diff especially when you've got more torque

[Limbo]

best price i could get for the T1rs was $165 in SYd

[EG5]

if you gonna run it down the 1/4 mile
just get m/t DOT drag radial or BF goodrich
both avail on 225/50/15 size.
Do it!

[beeza]

best price i could get for the T1rs was $165 in SYd

Thanks Limbo!
I'll keep hunting a better price :thumbsup:

[destrukshn]

as i've mentioned, contact patch doesnt affect dry traction. contact patch only has an effect on wet traction.

and you'd be suprised how much an effect cooling can have on quarter mile drags, remember how you are recommended to do a burnout before you make the run? if your tyres have poor cooling effect, you'll melt your tyres before you even make the run. good wide tyres should be able to remain at their ideal working temperature, which is why they have better grip.

and the people who dont use an intercooler on drags dont do it because they dont need its cooling functions, they do it for slightly better response.

R&D do look into the amount of heat dissipation the tyre will need, but there are legalities that restrict the type of compound that can be used on the street, as well as the width of the tyre you can fit under your guards, plus they accommodate for the occasional sporting outing that people take their cars on, they dont accommodate for cars thrashed on the hills non-stop for half an hour. there are far more factors than you're thinking of.
hahahaha
in the wet?
IF you have wider tyres in the wet, you will have more of a chance of aquaplaning.
lol.
dry is the wider you have the more contact surface so more traction, you think high powered porches, bmws, run 285-315 wide tyres for nothing? lol.

[SeverAMV]

hahahaha
in the wet?
IF you have wider tyres in the wet, you will have more of a chance of aquaplaning.
lol.
dry is the wider you have the more contact surface so more traction, you think high powered porches, bmws, run 285-315 wide tyres for nothing? lol.

different vehicles have different mass, which cause different amounts of loads to be place on the tyres, as well as the tyre geometry being altered, which is why they run wide tyres. you can fit wider tyres to every car and expect it to perform better. you need a wider contact area on the rain to help maintain traction, as well as tread patterns to clear the water away from the tyres. and as i've mentioned, fitting wider tyres =/= more traction, it just feels more stable if you've got a good width because the contact patch has deformed to be wider.

[dsp26]

Thanks Limbo!
I'll keep hunting a better price :thumbsup:

Blairs Tyres in Lansvale

[dsp26]

SeverAMV has very good points.... however I think camber should be corrected first to get the optimum contact patch if haven't done already before looking at other options....

I see people driving around on half a tyre all the time with uncorrected camber.... even if it looks flat, neg camber shifts all the weight to the inner of the tyre...

[TALEB TYRES]

If you guys are still chasing 215/45/15 we have the toyo T1S in stock, pm for details.(guaranteed best price in Australia ;)

<E240 Edit: Clarified that Taleb Tyres is now a new Ozhonda Merchant - Good luck with your sales>

[Limbo]

i have no camber issues, i got 5zigen shock and spring combo designed for ek9.

yeah the price i got is from Blairs in lansvale/cabra

[TALEB TYRES]

PM sent e240 about the 215/45/15
cheers

edit: thanks E240 for clearing it up :)

[Limbo]

PM sent!

[beeza]

I was going to get 205/50/15 T1r's.... bit confused now as what to get.What size would you guys recommend? It's for an EK1 Sedan.Street use and the occasional track day :)

[Killa From Manila]

i came across an article on the net that backed up alot of stuff serveramv is saying. its a good read, il try find it

[e240]

I was going to get 205/50/15 T1r's.... bit confused now as what to get.What size would you guys recommend? It's for an EK1 Sedan.Street use and the occasional track day :)

If you're running 15s, thats a good size to get. alternatively, you could get 195/55R15, but me, I'll go 205.

[[ricer]]

I was going to get 205/50/15 T1r's.... bit confused now as what to get.What size would you guys recommend? It's for an EK1 Sedan.Street use and the occasional track day :)

205/50r15 is good or 195/55r15

[fatboyz39]

i've got 215/45/15, that would be like a 205/50/15 i.e rollin diameter?

[beeza]

Thank U! I think the 205/50/15 then cause with the extra weight of a sedan I reckon I need the traction on those track corners :)
atm I runnin' 205's and it feels great except for the fact that I need to put a rear sway on,which I just recieved today in the post :)

[vinnY]

http://img107.imageshack.us/img107/9949/screenshot2gt5.jpg
teeny bit out :)

[Limbo]

that's fine cos 205/50/15 is already slightly smaller than 195/55/15.

The 215/45/15 is smaller again.

wanna get 215/50/15 but they don't really seem to make these

[beeza]

How about the 215/45/15 then.

[55EXX]

215/45/15 is fine that what i have. you getting the tyres from the market place thread? won't be disappointed

[Limbo]

215/45/15 is smaller than 205/50/15 which is smaller than 195/55/15

Will still work just need to be aware that you are not driving as fast as the car says, might save you some license points ;)

[beeza]

Hey,that's a good thing!

[dsp26]

i've got 215/45/15, that would be like a 205/50/15 i.e rollin diameter?

http://www.1010tires.com/TireSizeCalculator.asp :thumbsup::thumbsup:


http://img.photobucket.com/albums/v281/dsp26/sizes.jpg

[Killa From Manila]

http://autospeed.com/cms/A_108915/article.html

Tyres, Grip and All That...
Sorting fact from fiction in tyre physics
By Dennis Jensen

So many tyres; so many factors to consider! Do you go wider? Do you go for a lower profile? Do you increase your wheel diameter? What pressures do you run? The whole area is quite complicated, and the result is that there is a hell of a lot of misconceptions out there. What is needed is a primer to give some fairly solid grounding in the basics, so that informed decisions can be made.

So, let's go through two of the misconceptions, and see if we can get an understanding of what actually contributes to grip - and what does not.

Myth 1: Wider tyres have a larger contact patch than narrow tyres
What actually influences the size of the tyre's contact patch? Is it the width of the tyre, or the profile? The simple answer that it is neither of these; the size of the tyre's contact patch is related to:

the weight on the wheel
the tyre pressure.
For example, say that the weight on the tyre was 900lb, and the tyre pressure was 10 psi. That internal pressure means that each square inch of area can support 10lb, so, in this case, the contact patch will be 90 square inches. If the tyre pressure was 30 psi, the contact area would be 30 square inches, and if the pressure was 90 psi, the contact area would be 10 square inches. This has been found to be almost exactly correct for most tyres (the exceptions being so-called run-flat tyres, or tyres with extremely stiff sidewalls). For most other tyres, carcass structure will have an effect, but by far the major factor is tyre pressure.

So, as you can see, the size of the contact patch of a tyre is not related to the width of the tyre - it is, in fact, proportional to the tyre pressure. What will change with the fitting of a wider tyre is the shape of the contact patch - it will get wider, but shorter longways.

Myth 2: A larger contact patch = more grip
Okay, most people will come to the conclusion that if you have "more rubber on the road" you will have increased grip. Sorry to say this folks, but to very close to 100&#37; accuracy, the size of the contact patch is irrelevant.

The actual grip that a tyre can generate is dictated by the coefficient of friction of the rubber compound used in the tyre. The higher the coefficient, the more grip which can be generated. The relation that is used is called Amonton's Law, and the equation is:

F=uN,

where F is the force generated, u is the coefficient of friction, and N is the weight on the surface considered (in our case, the weight on the tyre).

So, if you increase the weight on the tyre, then the frictional force will increase as well, in proportion to the increase in weight on the tyre - but the coefficient of friction will remain the same. The level of grip of the tyre (forgetting about suspension niceties - we are only discussing tyres here) is totally dictated by the coefficient of grip of the tyre and the weight acting on it - not the area of the contact between the tyre and the road.

Why Not Narrow Tyres, Then?
So, I hear you argue, why bother with wide, low profile tyres at all? Why not simply have narrow, high profile tyres? The simple reply to that is heat (remember, we are simply talking grip here, not the niceties of handling finesse). The point is that, to get a contact patch of a certain size on the road, you need a certain portion of the tyre to be flat. Taking the contact patch to be basically rectangular (though it is actually partially oval in shape), then the area of that patch will be its length times its width. Now, for a narrow tyre, the contact patch will be quite long compared with a wide tyre.

This introduces two problems for the tyre.

First, to get that long flat section to give the required contact patch, the sidewall of the tyre needs to deform quite a lot. This deformation actually causes the bending and unbending the rubber of the sidewall as it flattens and then the tread curves again. This bending and unbending process results in a lot of heat being generated. (Think about bending and unbending a piece of wire rapidly, and how hot it gets as you do so. If you bend it less, but at the same frequency, less heat will be generated). Obviously, the more it needs to bend, the greater the amount of heat generated.

The second relates to the length itself. There will be a greater percentage of the tyre tread in contact with the road than if the contact patch length were shorter; this reduces the amount that the tread can cool. Also, there is a greater percentage of sidewall at any given time that is actually under bending stresses, again resulting in less opportunity to cool.

So, how much extra bending do you really get, and how much is potential tread cooling reduced? Let's take a theoretical example, and take a 155-width tyre compared with a 225 tyre of the same circumference. Agreed, this is an extreme example, but it will suit our point very well. Assume that the wheel/tyre-unloaded circumference is 60cm. Assume the tyre pressure is 30 psi, and that the weight on the wheel is 600lb, giving an area of 20 square inches (or 129 square cm). Assuming that the contact patch is rectangular, with the wider (225) tyre, the patch will be 5.73cm long, and with the 155 tyre, the patch will be 8.32cm long. Now, the circumference of the wheel-tyre combination is 188cm, so the 225 is heating for 3% of its cycle, and cooling 97%, whereas the 155 is heating for 4.5% of the cycle and cooling for 95.5%. So, you can see that the narrower tyre is generating heat 50% longer than the 225, and is not spending so much of its cycle cooling.

Now, as far as heating of the tyre is concerned, simple geometry shows us that the 155 tyre bends by 0.29cm, and the 225 bends by 0.14cm. Now, assuming that the heating of the tyre is roughly proportional to the deformation, let's find out the results of all of this. We will multiply the deformation by the percentage of time the tyre sidewall is under stress, and divide this number by the percentage of time that the tyre is being cooled. Multiplying the resulting numbers by 100, we get a figure of 1.37 for the 155 tyre, and 0.43 for the 225. Dividing the 155 tyre's number by that of the 225, we find that the heat generation of the 155 is 3.2 times that of the 225! This is quite an amazing result, given that the 225 is only 45% wider than the 155.

As a result on this increased generation of heat, and the reduced capacity for self cooling, the tyres need to be made of a harder rubber compound that is more able to resist heat. This harder compound will, of necessity, have a reduced coefficient of friction, particularly when cold. The tyres that are wider can have a softer compound with better frictional properties. Due to the reduced bending stresses, and greater cooling opportunities, the tyre will tend to stay within a narrow temperature range quite consistently, giving greater cold grip, while managing to have a reduced propensity for overheating. Obviously, this makes for a better performance tyre.

On the issue of wheel size (the diameter, not the width), it is therefore clear that increasing the wheel/tyre diameter combination is beneficial. The reason for this is that the tyre will not have to deform so much to get the required contact patch length, and the percentage of the tyre tread in contact with the road will be less than for a smaller diameter combination.

So, what about tyre pressure? Obviously, tyre pressure plays a very important part, but there are clearly limits on both sides of the tyre pressure equation. At the higher end, there is the maximum tyre pressure that can be sustained before there is damage to the carcass. At the low end, you don't want the sidewall almost collapsing, generating massive heat, and have the tyre slipping on the rim. So, you can play around with tyre pressures to optimise your set-up, but there are limitations.

A simple way to find out approximately what pressure is optimal for your combination is to draw a chalkline across the width of the tyre, drive for a bit, and look at the wear pattern of the chalkmark. Wearing more quickly in the centre indicates pressure that is too high, and wear on the edges indicates too low a pressure.

One issue to consider is that, for wet weather driving, despite what you may have heard, it is better to increase your tyre pressure, not reduce it. The reason is that there is a relationship between tyre pressure and the speed at which there is the onset of aquaplaning. In the Imperial system, the equation is 9 times the square root of the tyre pressure. So, if your tyres are at 25 psi, if you drive into a puddle that is deeper than your tread depth, you will aquaplane at 45 mph (72 km/h), whereas if your tyre pressure was 36psi, you would aquaplane at 54 mph (87 km/h). The advantages are obvious.

As far as tyre profile is concerned, the main benefit is one of handling - the lower sidewalls give reduced sidewall deformation under lateral loading, which results in improved steering response and a more stable contact patch.

Conclusion
Summarizing, what factors are important in terms of tyre grip? Tyre width has no direct relation to the amount of grip generated; it is a secondary factor, and the width basically relates to cooling potential and so the tyre compound that can be used. The size of the contact patch has no bearing on the amount of grip generated at all, apart from the extreme of where the compound is getting so hot that it no longer acts as a solid (and therefore doesn't follow Amonton's Law). The tyre pressure has no direct bearing on the level of grip (apart from aquaplaning), but it does have a bearing on the heating and cooling characteristics of the tyre. Having a lower tyre profile gives improved handling through reduced sidewall stress and improved contact patch shape stability.

[beeza]

Hey hey hey back to Physics Class :)
I'm glad I'm getting the 215/45/15's since what it says in the last sentence.

[rahul]

i think you should also consider the rim width. you wouldnt want to put too wide of a tyre as it will increase the pressure on the side wall.

the yokahama website shows the min ideal and max tyres you can have on a particular rim width

[beeza]

Have U got a link? I couldn't find it on the Yokohama website...

[Limbo]

max on a 6 1/2" is 225. You should be fine

[beeza]

Thanks Limbo,I was starting to worry (but I knew I would be sweet).Should get my T1S's tomorrow! WOOT WOOT! :)

[rahul]

just FYI

http://www.yokohama.com.au/ourtyres/

go to any tyre product line and click on the sizing chart

[JohnL]

Tyres, Grip and All That...
Sorting fact from fiction in tyre physics
By Dennis Jensen

“So, if you increase the weight on the tyre, then the frictional force will increase as well, in proportion to the increase in weight on the tyre - but the coefficient of friction will remain the same. The level of grip of the tyre (forgetting about suspension niceties - we are only discussing tyres here) is totally dictated by the coefficient of grip of the tyre and the weight acting on it - not the area of the contact between the tyre and the road.”

There's a lot of sense in this article, and a lot I agree with and have read elsewhere, but the statements in the above paragraph are in contradiction to everything I can ever recall reading relating to this specific aspect of tyre performance.

From my reading, my understanding is that as loading increases on a fixed size contact patch, the co-efficient of friction increases, but not in a linear relationship with the increase in loading, contrary to the article’s statement.

To use some arbitrary numbers (meaningless in themselves since they aren't 'data', only numbers plucked from thin air to illustrate a general principle); if you were to increase loading on a contact patch by say 100% then the co-efficient of friction may increase by say 50% (not 100%). If you were to decrease the contact patch loading by say 50% then the decrease in co-efficient of friction would be say 25% (not 50%). I'm sure it's not that simple nor that progressive, if it was then you'd still have some friction even if you reduced loading by 100%, which is clearly impossible.

However the non linear affect must exist because if this weren't the case then weight transfer (as it affects overall chassis grip) wouldn't be an issue, and the CG height and track width wouldn't matter (beyond the car tipping over). If grip didn't increase in a non linear manner with increased loading (as opposed to a purely linear manner as stated in the article), then the car would grip just as well with all it's weight transferred to the outside wheels as it would if little (or no) weight transfer occurred, which clearly isn't the case otherwise there would be no point in lowering the CG or widening the track width in order to decrease weight transfer and thus to increase potential lateral grip and lateral acceleration.

With a purely linear contact patch loading / grip model there would be no difference in total chassis grip with the car generating 100% of it's grip from the two outside tyres alone, or generating say 75% of it's grip from the outside tyres and 25% from the inside tyres, the peak possible total grip would be the same.

With a non linear contact patch loading / grip model the car will generate more total chassis grip as a result of having less weight transfer and in effect 'more rubber on the road', up to the point at which the inside contact patches become fully unloaded (which with a lower CG and / or wider track may not even be reached before total grip loss at all four contact patches, but at a higher lateral acceleration than with a higher CG and / or track width with total unloading of the inside contact patches).

With a purely linear contact patch loading / grip model we would also be unable to tune understeer / oversteer characteristics by altering the balance of front / rear roll stiffness, and thus altering the %s of total chassis weight transfer that occurred at the front and the rear axle lines, thus altering the ratio of effective 'rubber on the road' front vs rear, i.e. the more equally loaded the two contact patches are the more grip they will generate at that axle line, and the less equally loaded the less grip will be generated at that axle line (which is why altering front vs rear roll stiffness changes the understeer / oversteer balance).

If this is correct, then all else being equal increasing contact patch area must result in an increase in grip.

[Limbo]

thanks John, that was my understanding also