Tyre foot print question
tomgregory2000 - 30/4/10 at 02:17 PM
ok im looking to sort out my wheels and tyres due to the increased bhp and torque from my new engine 
now this is on a viento so if anybody says that i need 13" rims i will have to come round and slap you 
now to my question:
which one of these tyres would give me the biggest foot print?
245/55/16 on a 7" wide rim (yes they will fit) running 18psi OR
255/40/17 on a 9" wide rim running 18psi
now i guess the 16" rims and tyres will be lighter but being a viento its not the lightest of cars, all i want is the biggest contact area to try
and cut down the wheel spin in first, second and third
in my mind i am thinking the 245/55/16 will give me the biggest contact area but what does everybody else think?
l0rd - 30/4/10 at 02:24 PM
245/55/16 would be the ones to go for.
ignore my comment
The biggest area would be the 255/40/17
I would still go for the 16 though
[Edited on 30/4/10 by l0rd]
Canada EH! - 30/4/10 at 02:25 PM
Well if 245 is the tread width and 55 is the side wall to tread ratio, then I think the 255/40's will put more rubber on the road. Having said
that, the 40's side wall is going to make for a very hard ride. This is the reason people recommend 13" tyres, large side wall works as part
of the suspension.
Richard Quinn - 30/4/10 at 02:46 PM
Sorry, hijack alert! My lad is after some 245/40 17's for his van (don't ask!!!). I don't have much experience of these sorts of sizes
so where's best to go for these large rubber bands?
40inches - 30/4/10 at 02:57 PM
quote:
Originally posted by Canada EH!
Well if 245 is the tread width and 55 is the side wall to tread ratio, then I think the 255/40's will put more rubber on the road. Having said
that, the 40's side wall is going to make for a very hard ride. This is the reason people recommend 13" tyres, large side wall works as part
of the suspension.
Good job you are in Canada or Tom would be over to yours to give you a good slapping
tomgregory2000 - 30/4/10 at 03:13 PM
i dont mind going over to canada to give um a slap just as long some one can pay for my flights
anyway back to my original question.
i know 255 is 10 wider than a 245 but with a higher profile of the 245's and running 18psi you would get more tyre contact front to back than on
the 255's
alistairolsen - 30/4/10 at 04:43 PM
The tyre contact patch are will be identical whether you fit 145 or 330 wide tyres.................
40inches - 30/4/10 at 06:04 PM
quote:
Originally posted by alistairolsen
The tyre contact patch are will be identical whether you fit 145 or 330 wide tyres.................
Then why fit bigger tyres, why don't all cars run on 145's if it doesn't make any difference?
Canada EH! - 30/4/10 at 06:50 PM
Have him come over I haven't had a good rumble since I retired from the Toronto Police.
v8kid - 30/4/10 at 07:11 PM
215/50/15 888's (worn but legal) on 7J team dynamics pro 1.2 and Khumo 275/40/17 (dyno run only) on 9J TD pro 1.2 available half price of rims
alone U2u if interested all standard ford fitment
[Edited on 30-4-10 by v8kid]
Stott - 30/4/10 at 08:14 PM
quote:
Originally posted by tomgregory2000
i dont mind going over to canada to give um a slap just as long some one can pay for my flights
anyway back to my original question.
i know 255 is 10 wider than a 245 but with a higher profile of the 245's and running 18psi you would get more tyre contact front to back than on
the 255's
I'll come too if flights are paid, my days as a paid assasin are over and im getting bored in the garage all day, lol
tomgregory2000 - 30/4/10 at 10:05 PM
quote:
Originally posted by v8kid
215/50/15 888's (worn but legal) on 7J team dynamics pro 1.2 and Khumo 275/40/17 (dyno run only) on 9J TD pro 1.2 available half price of rims
alone U2u if interested all standard ford fitment
[Edited on 30-4-10 by v8kid]
you have u2u
nz_climber - 1/5/10 at 01:28 AM
I would suggest the 16's, as with the bigger sidewall aspect, you will have more movement in the sidewall that will help traction off the line a
lot more than 10mm extra width.
Gives more side wall to deform, before spinning the wheels - check out slow motion top fuel drag cars launch to see what I mean.
Frosty - 1/5/10 at 12:39 PM
quote:
Originally posted by 40inches
quote:
Originally posted by alistairolsen
The tyre contact patch are will be identical whether you fit 145 or 330 wide tyres.................
Then why fit bigger tyres, why don't all cars run on 145's if it doesn't make any difference?
He didn't say it doesn't make any difference. He just said the contact patch will be the same no matter how wide the tyres are (assuming the
same tyre pressures).
What will change is the shape of the contact patch though, which is where it gets interesting.
40inches - 1/5/10 at 01:26 PM
quote:
Originally posted by Frosty
quote:
Originally posted by 40inches
quote:
Originally posted by alistairolsen
The tyre contact patch are will be identical whether you fit 145 or 330 wide tyres.................
Then why fit bigger tyres, why don't all cars run on 145's if it doesn't make any difference?
He didn't say it doesn't make any difference. He just said the contact patch will be the same no matter how wide the tyres are (assuming the
same tyre pressures).
What will change is the shape of the contact patch though, which is where it gets interesting.
That's what I have always understood, that the contact patch gets wider and thinner as the tyre width increases "at the same tyre
pressure" therefore to increase the contact patch area the pressure is reduced. Correct?
I'm not being arsey by the way, just very interested
Frosty - 1/5/10 at 07:58 PM
quote:
Originally posted by 40inches
That's what I have always understood, that the contact patch gets wider and thinner as the tyre width increases "at the same tyre
pressure" therefore to increase the contact patch area the pressure is reduced. Correct?
I'm not being arsey by the way, just very interested
That's right, the only ways to actually increase the contact patch of the tyre are:
a) Reduce the tyre pressure.
b) Increase the weight on the tyre.
If a tyre is inflated to 30 lbs per square inch, each square inch of tyre is supporting 30lb of weight.
So if you have 200lb of weight on a tyre inflated to 30psi, you have a contact patch of 6.66 square inches. If you have a 185 tyre, the contact patch
will be 7.3 inches wide, and (if I have done my sums right) 0.91 inches long.
The contact of a 235 tyre would be 9.25 inches wide, and 0.72 inches.
So the contact patch is always the same, but the shape of it is different.
Angel Acevedo - 3/5/10 at 03:32 AM
quote:
Originally posted by tomgregory2000
ok im looking to sort out my wheels and tyres due to the increased bhp and torque from my new engine
now this is on a viento so if anybody says that i need 13" rims i will have to come round and slap you
now to my question:
which one of these tyres would give me the biggest foot print?
245/55/16 on a 7" wide rim (yes they will fit) running 18psi OR
255/40/17 on a 9" wide rim running 18psi
now i guess the 16" rims and tyres will be lighter but being a viento its not the lightest of cars, all i want is the biggest contact area to try
and cut down the wheel spin in first, second and third
in my mind i am thinking the 245/55/16 will give me the biggest contact area but what does everybody else think?
I think you could use softer tires