Tire Size Guide

[newbien]

i was just thinking it would be good to get a list of what tyre sizes people have found are effective on different width rims....

i have found that for the front...
175/60/14 is very good grip and response
and for the rear...
175/65/14 for the rear is good for both grip and slide
on my 14x7's

[andurils_sheath]

I wouldve thought wider would have been better, I mean my 14x6s fit 185 rubber, so id assume you could fit 195 or 205 rubber on 14x7s.

just food for thought.

Well i run,

175 65 R14 on the front and
185 60 R14 on the rear,
on 14x6 Challengers

keeps them in spec with the original rubber so hopefully my speedo is close to correct.

[oldcorollas]

i was just thinking it would be good to get a list of what tyre sizes people have found are effective on different width rims....

i think you'll find that tyre manufacturers recommend a certain rim width for each tyre..

175 on a 7" rim? perhaps that works with big sidewalls, especially if you are after that fooly sik dorifto look, but the 215/45/17's i have on a 7" rim look perfect... they are decent tyres tho, bridgestone RE-01R's, with very solid sidewalls, so the rim fit needs to be very good.

i find it curious that you say a 60/65 series tyre is good for response? don't the fat squishy sidewalls (stretched to fit your rims?) have a fair bit of give in them?

[wilbo666]

i have found that for the front...
175/60/14 is very good grip and response
and for the rear...
175/65/14 for the rear is good for both grip and slide
on my 14x7's

Dang, tyre companies have recommended tyre fitment guides.

Toyo recommends a rim width of 5" -> 6" for 175/60/14 sized tyres...a 7" rim seems a little outside that, sure a stretched tyre looks good, but I think u might be pushing it a little far

Cheers
Wilbo

[Cameron_Datto]

I found this web page very Handy for working out tyre Dia and width ....its the best one i have found so far ..
http://www.miata.net/garage/tirecalc.html

[oldcorollas]

this is another very very good page about tyres and rims... best i have seen so far
http://www.carbibles.com/tyre_bible.html

Aspect Ratio and Rim / Pan Width.
Aspect ratio is, as you know if you read the bit above, the ratio of the tyre's section height to its section width. The aspect ratio is sometimes referred to as the tyre 'series'. So a 50-series tyre means one with an aspect ratio of 50%. The maths is pretty simple and the resulting figure is stamped on all tyres as part of the sizing information:

Aspect ratio = Section height / Section width

The actual dimensions of a tyre are dependent on the rim on which it is mounted. The dimension that changes the most is the tyre's section width; a change of about 0.2" for every 0.5" change in rim width.

The ratio between the section width and the rim width is pretty important. If the rim width is too narrow, you pinch the tyre in and cause it to balloon more in cross-section. If the rim width is too wide, you run the risk of the tyre ripping away at high speed.

For 50-series tyres and above, the rim width is 70% of the tyre's section width, rounded off to the nearest 0.5.

For example, a P255/50R16 tyre, has a design section width of 10.04" (255mm = 10.04inces). 70% of 10.04" is 7.028", which rounded to the nearest half inch, is 7". Ideally then, a 255/50R16 tyres should be mounted on a 7x16 rim.

For 45-series tyres and below, the rim width is 85% of the tyre's section width, rounded off to the nearest 0.5.

For example, a P255/45R17 tyre, still has a design section width of 10.04" (255mm = 10.04inces). But 85% of 10.04" is 8.534", which rounded to the nearest half inch, is 8.5". Ideally then, a 255/45R17 tyre should be mounted on an 8½x17 rim.

An ideal rim-width calculator
Blimey I'm good to you. Can't figure that maths out either? Click away my friend and Chris's Rimwidthulatortm will tell you what you need to know.

Too wide or too narrow - does it make a difference?
Given all the information above, you ought to know one last thing.
A rim that is too narrow in relation to the tyre width will allow the tyre to distort excessively sideways under fast cornering. On the other hand, unduly wide rims on an ordinary car tend to give rather a harsh ride because the sidewalls have not got enough curvature to make them flex over bumps and potholes. That's why there is a range of rim sizes for each tyre size in my Rimwidthulator above. Put a 185/65R14 tyre on a rim narrower than 5inches or wider than 6.5inches and suffer the consequences.

and from the approx above, the 85% gives 7.2" as my ideal rim... (bridgestone recommend 7", with 7-8" possible)

edit2: and bridgestones approved rim width for 175/65/14 is 5" to 6", with the recommended size being 5"

[newbien]

the 175/60/14 are toyo trampio's

they have pretty stiff sidewalls, they arent really that stretched, they are about the same as a 185/55/14 on a 7 inch wide rim

[newbien]

the actual recomended size in the book for a 7 inch wide 14 is 195/65 or 205/60

[oldcorollas]

the 175/60/14 are toyo trampio's

they have pretty stiff sidewalls, they arent really that stretched, they are about the same as a 185/55/14 on a 7 inch wide rim

bugger
http://www.toyo.com.au/
they also say 5-6", and their test rim was 5"....
but.. whatever works for you

[takai]

Aye, 195/60/14s work quite well for me on 14x7 rims. But then again they are control tyres, they ought to work well. Plus with the 60series sidewalls it gives some flex which is useful as suspension of sorts.

[newbien]

i used to run 195/60's, that was trampio's too, over 14x7', too much guard scrape for my application, thats why i changed over to something that had a bit more stretch to keep it under the guards

[Ta22boy]

Hey,
When changing tyre sizes you need to basicly keep the same rolling diameter as what the car was originally fitted with so that the speedo isnt out. Meaning if your car originally comes with a 175/70/13 and you want to run 15's then you would need to run 195/50/15's or 205/45/15's. I dont know the actual formula, but it basiclly works out to the larger width of the tyre, it needs to have a smaller sidewall to keep the rolling diameter the same meaning if you go up one size in width, 175 to 185 then you would need to drop the sidewall width from 65 to 60, you can basicly work it out from that, so just remember you can go up a few sizes in width but you will have to drop the sidewall width the same amount of sizes.But it all honesty you have to change the size of the tyre quite a bit to put the speedo out more then 5-10km either way. Also from working as a wheel aligner, i have actually fitted up to a 225/50/15 on a 6'' rim, the sidewall bulges out but is possible, not that great but you can really stretch some tyres so fitting tyres that arent meant for a certain rim is possible, but try to go to big or too small on certain rims can end very badly. Also it really depends on what sort of power you have and how you drive by putting 175/60/14's on a car with decent power would just spin like crazy, but on the front might give better response but less traction especially in the wet. Obviously the smaller the sidewall the less sideways flex in the tyre therefore better handling but you do feel the bumps a bit more. But it really comes down to what you want the car to do and how you want it to handle in different situtations. Anyways just thought i would bring up the rolling diameter so that people still have working speedo's!!...
Also if i can suggest some tyres, go the Yokohama A539's or GSD3 eagle F1's most tyres will do the job but these really handle the wet and dry very well...

[Ta22boy]

I wouldve thought wider would have been better, I mean my 14x6s fit 185 rubber, so id assume you could fit 195 or 205 rubber on 14x7s.

just food for thought.

Well i run,

175 65 R14 on the front and
185 60 R14 on the rear,
on 14x6 Challengers

keeps them in spec with the original rubber so hopefully my speedo is close to correct.

Yeah your right about the specs there by running the larger tyre on the rear with the smaller sidewall to keep your speedo right. Also you can seriously fit 215's on a 6'' rim without too much hassle and on a 7'' i would even go up to a 235 as my limit, any more then that, too much stretching of the tyre for my liking!!

[newbien]

what is so important about keeping your speedo dead accurate???
i thought we were here to modify
if you are that worried about it get your speedo re-calibrated
my 3.2c worth

[Yian]

i was just thinking it would be good to get a list of what tyre sizes people have found are effective on different width rims....

i have found that for the front...
175/60/14 is very good grip and response
and for the rear...
175/65/14 for the rear is good for both grip and slide
on my 14x7's

Wow god dang.

My 14 x 7s

Front with Yokohama a509s (225/60/14)
Rears with Firestone of some sort (235/60/14)

The Yokos are bloody great. Sticks to the road like nothing else and the Firestones are pretty good considering the price.

Meh. Maybe I just don't like to slide.