Wheel & Tyre Guide; Widths, Diameters, Sizes in General and what you can and can't fit on your stock and mag rims.

How to read your Tyre Size!
The writing on your sidewall shows a sequence of numbers which really mean your width, diameter and profile of your tyre for your rim.

example 205/60/15 (or 205/60R15)

'205' is the width of the tyre (where the tread is) in mm.
'60' is the tyre profile itself (from ground to rim eg.) in mm.
'15' / 'R15' is the rim size, in inches.

So in english. 205mm (20.5cm) is your width of your tyre, 60mm (6.0cm) is your running profile, and 15" (inches) is your rim size. Say for a common 17" rim it'd say 235/45/17. (meaning 235mm [23.5cm] wide, profile of 45mm [4.5cm] and rim size is 17").


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Falcon Wheel Info;

Stock 15" Wheels (Found on all EA-AU) can fit 225/60/15's on all fours. Although myself and others usually just do a 215/60 on the front and 225/60 on the rear. You will definately notice the difference in handling and body roll/tyre roll from the stock 205 size. (Note: Police/Taxi's use 215s as standard on all their vehicles). And if your lowered and can't or not want to get rims for sleeper purposes the extra width of these tyres will give you a nicer grip on the road.

17" & 18" & 19" Mag Wheels on a falcon you can go 245 (width) up front, and 255 (or 265 which i have if your not to low and rear guards are rolled) for the rears. Most commonly wheel/tyre package sold is 235/45/17 though for a 17" rim. **NOTE: Roll your guards on the front if you are lowered then "lows" or even lows too as your guards WILL be ripped out by a bounce on a corner and the tyre hitting it, alternatively your tyre will be eaten out on the sides.

Of course going from a 15" stock wheel to a 16", 17", 18" rim which is 7-8.5" (inches) wide will allow a wider tyre and of course much more grip. Keep in mind, the larger the wheel you go the slower your take off is as the rolling diameter of a larger wheel obviously takes LONGER to roll along. Hence why when people doing quarter mile runs they change to 13/14/15" (inch) wheels to allow the wheel to spin quicker and move along.

Myself i have 18"x8" wheels, i have 245/40's on the front, and 265/40s on the rear giving me a fair bit of traction. Although you definately can notice how much more a 15" takes less effort to move then these! (Weight too!)

Pricing of tyres of course becomes more and more expensive when you get to the mag wheels. Personally i suggest if you want large wheels take in mind that you will need new tyres and they aren't cheap, alternatively its better just getting second hand ones which are bout $55-90 for half decent tyres (Bridgestone, Dunlop, Michelins, Pirelli, so on). Considering half these tyres cost rrp$250+ea your getting a bargain. Cheaper tyres you will definately notice the difference on traction in the dry and MORE then ever in the wet. Comparing a Michelin Primacy ($495+ea) to a Nankang ($145+ea) isn't even possible, your nankang could not compete with traction at all or safety. Safety and braking ability also comes from good traction and tyres (DUH). So if you can't afford new, try s/h. (NOTE: i highly recommend not getting Falken tyres as they cause uneven road wear, and high tyre noise on fords for some reason, holdens too)

In Sydney i'd say try Tyre Express on 9892-3587 in South Granville, or 7 Day Wheel & Tyres in Auburn. But there's PLENTY of other places around Sydney and other Cities in AUS who have second hand tyres! check tradingpost is your best bet.

Hope that give bit of a run down and info, any questions feel free to ask.

Im sure theres a lot more experienced people regarding this, so more info and help for others would be appreciated and good! Just my quick run down for everyone to help out

I thought profile was expressed as a percentage of the tyre width?

Yes, it is.

Also note that people choose larger diameter wheels and use lower profile to reduce tyre roll, and at the end of the day the outer rolling diameter of the tyre isnt varied by much at all.

Hmm ive just changed all the tyre profiles on my XR6 this week and its handling the best its ever been. Fronts were 215/65/15 now are 205/65/15 and rears are 225/60/15's were 215/65/15's.. All Yokohama Performance treads too! Cost a fair bit $650 for all four.

Good work thier fusion.

i was just looking at some online tyre size calculators, (should include one in your post...

how is it that the tyre diameter as in 225 for example effects the speedo reading? how does that change the rolling circumference of the wheel?

http://www.miata.net/garage/tirecalc.html

*meh* the profile's relationship with rolling diameter always confuses me (i'm a bit 'simple' ).

Good write up fuzion. Im interested to know your preference in manufacturer... 265s on the rear, safe to say you take your traction fairly seriously!!

ah yes, so the profile is a % of the diameter, after reading fuziosn post i was gettin confused as why it changed hehe, but makes perfect sense...

now all you have to do is change that little part and everyone is happy

no - just me!
good doco btw Pierre

If you change profile you should change the speedo gear of course, but 80% of people never bother.

If you have a exchaser cluster you can do so through that, but otherwise .. eh LOL

As brad said, from a 15" with stock profile to a 17" your diameter is pretty much the same.

And Martin, yeah. but i still loose traction and i have p-zero's on the rear! what the!

and also remove the part about changing diameter of rim affecting quarter mile times, coz a 205/65R15,225/50R16 and 235/45R17 all have pretty much the same diameter.. and if you vary the wheel diameter more than 5(??)% its illegal anyway.

and add the fact that when going to 16/17/18 inch rims, the width of tyre you can go to depends entirely on the width of that rim at that size. example: a 17x7.5 will go up to 245 tyre width. you'l need a 17x8 to get 255 width.

as the rim size goes up and profile goes down, the width of the tyre will have to be closer and closer to the rim width. you can fit a 235 on a 15x6.5"(std ed ghia) rim even tho 235 is 9.25" wide. the difference there is nearly 3 inches. the max you can get on a 17x7.5 is a 245, yet that is only 2.1 inches more than the rim width.

not sure about 18inches, but going on that im not suprised that i havent heard of a 255 tyre on an 18x8" wheel.

there used to be heaps of info on the bridgestone site, namely fitment guides.. you could see what tyres fit on what sizes of rims(im talking specifically about width).. very handy. but they've long upgraded their site n removed all of that. to get that info you'l have to call a tyre place.

This tyre size calculator is handy in working out how much the speedo will be changed. {DESCRIPTION}

glad to see all the input, i left out info to hear other peoples views/input as well (easy way to get responses LOL)

phwoar i didnt know i could get 265's on my car......I think ill get some prices tmrw....not on p zeros though

a 215/60/R15 means that it is a radial tyre, designed to fit a fifteen inch rim and nothing else. The width of the tyre is 215mm, and the sidewall height is 60percent of that, or around 130 mm. Also take note of things like speed ratings, and load ratings. Never buy cheap tyres if you can help it!