Tires

rnbboi · Post by **rnbboi** » Fri Oct 27, 2006 12:20 pm

Hi guys,

Just wondering what would be the advantages and disadvantages of changing the tyres to a lower profile.

** I am not looking for opinions in terms of looks etc **

I know that generally if i was to lower the profile of the tyres, the load rating would drop, just say... from 89V to 87V. Is this dangerous?

And what if I went from 205 to 215, any problems or benefits from that?

Thanks.

Post by **Bennoz** » Fri Oct 27, 2006 12:26 pm

Going to a smaller profile generally helps handling as you loose side wall 'roll' when cornering, but it comes at the cost of comfort. It will be a bumpier ride.

It never hurts to have a little more width on the road - say going from 205 to 215. Having said that, going too wide can lead to a car the might enjoy a little aqua-planing.

mxysxy · Post by **mxysxy** » Fri Oct 27, 2006 12:38 pm

There is so much about the profile of the tyres then I ever though before,
It all depends on your application again,
Here is my dilemma,
All above Bennoz said is absolutely correct, but,
According to my research, the smaller the profile the harder for your car to put the power down.
The side walls helps to reduce the traction loss, thatâ€™s why you donâ€™t see the drag race cars with small profile tyres, in fact they choose the largest profile, before loosing the shape. And again, same thing with race cars.

But in this case, FTO is not much power anyways,

rnbboi · Post by **rnbboi** » Fri Oct 27, 2006 12:39 pm

i see...

thanks for the info.

i opened the door of the car, and it said that i should not use tyres that has a load rating below of what it has specified.

so just say i did went for a tyre that had a lower load rating - does it matter?

Post by **Bennoz** » Fri Oct 27, 2006 12:43 pm

Very true, you don't see a V8 supercar running a 35 series tyre... its more like a 65 series tyre.

Also has a lot to do with pressure. Top fuellers run about 4psi.... the tyre bags right out on launch, getting as much rubber on the track as possible. Plus the heat that goes into them also causes the pressure to rise during the run.

Post by **Bennoz** » Fri Oct 27, 2006 12:46 pm

From Tirerack:

Load Index

P195/60R15 87S - The load index (87) is the tire size's assigned numerical value used to compare relative load carrying capabilities. In the case of our example the 87 identifies the tires ability to carry approximately 1,201 pounds.

The higher the tire's load index number, the greater its load carrying capacity.

89 = 1,279 pounds
88 = 1,235 pounds
87 = 1,201 pounds
86 = 1,168 pounds
85 = 1,135 pounds

A tire with a higher load index than that of the Original Equipment tire indicates an increase in load capacity. A tire with a load index equal to that of the Original Equipment tire indicates an equivalent load capacity. A tire with a lower load index than the Original Equipment tire indicates the tire does not equal the load capacity of the original - ie thats bad

rnbboi · Post by **rnbboi** » Fri Oct 27, 2006 12:50 pm

A tire's first requirement is that it must be able to carry the weight of your vehicle. No matter how good a tire you select, if its capabilities are "overworked" just carrying the load, it will have little reserve capacity to help your vehicle respond to quick emergency. So when you are in the selection process, make certain that your new tire's size is designed to carry the weight of your vehicle! Don't undersize.

the above was taken from http://www.tirerack.com/tires/tiretech/ ... ?techid=31

so im guessing i shouldn go for a lower profile then huh?

** oops, your post just went before mine ben, lol **

thanks for the info

khunjeng · Post by **khunjeng** » Fri Oct 27, 2006 2:38 pm

also the lower profile might give u a bumpy ride...the higher profile will help to absorb some shock .

SG · Post by SG » Fri Oct 27, 2006 2:43 pm

the reason race cars (circut etc) dont go a lower profile is because they dont need it afaik, semi-slicks and slicks have a much tougher side wall so they dont need as lower profile to get the same result

depends on how much ya car weighs to what profile is best i reckon cos thats what shifts during a corner... eg. a 1700kg passenger car compared to a austin mini - the mini wouldnt need low profile tires but the passenger car (ford gtp or something) could use 18's and low profile rubber to better effect.

someone on here has tested 16" semi slicks for the fto and said they had the best feel on the track, so the equal to that might be 17" normal road tyres...

rnbboi · Post by **rnbboi** » Mon Oct 30, 2006 9:21 pm

bringing this back up again...

does that mean most poeple that have traded in for a better set of blings running low profile tires should be concerned about their safety?

cos ive noticed that most people with aftermarket wheels run low profile tyres which i am sure that the load rating would be underrated compared to their stock rims/tyres

any problems to this?

i want to switch from a 45 profile to 40 profile tire, but everything indicates to me that i shouldn do this cos its like a drop from 89V to 84V

payaya · Post by **payaya** » Sat Nov 04, 2006 7:02 pm

the reason for low profile tyres is because it looks better.

You will be able to get better handling from a tyre with less of a profile.

There is no advantages from low profile tyres, except for the looks.

rnbboi · Post by **rnbboi** » Sat Nov 04, 2006 11:33 pm

got my new tires, decided to get 225/45/r17. dont wry, its not for the fto if u thinking of the size issue

Nacho · Post by **Nacho** » Mon Nov 06, 2006 9:15 pm

You also have to bear in mind that if you get larger rims then you either have to opt for flared guards to fit the wheels or you reduce the profile of the rubber so it doesn't rub under full steering lock. It will also reduce the need to lower the car coz it's obviously gonna raise your ride height if you use the same profile.

khunjeng · Post by **khunjeng** » Tue Nov 07, 2006 9:44 am

Nacho wrote:You also have to bear in mind that if you get larger rims then you either have to opt for flared guards to fit the wheels or you reduce the profile of the rubber so it doesn't rub under full steering lock. It will also reduce the need to lower the car coz it's obviously gonna raise your ride height if you use the same profile.

not if its stock hight...I doubt he will have an issue with 17s. My line has 18s and FTO 17s both are fine...

But if u want to lower it in a major way...the answer is yes...your offset and width will determine this also...cos if u have an offset that sticks out you may need to roll your guard aka me.

FTO338 · Post by **FTO338** » Tue Nov 07, 2006 11:03 am

Chris is right and you wouldn't want to just lower the profile of the tyres with the same rims, as the accuracy of your speedo will be out.

Daz_FTO · Post by **Daz_FTO** » Wed Nov 08, 2006 1:12 pm

from what i have heard elsewhere, always get a tyre rated to the correct weight and speed rating... going lower than spec could be dangerous and could earn a defect notice...

Rim + tyre wall heaight should always match whatever the overall diameter was within a small error...

found a brochure from Queensland Transport on modding cars - page 11, 12 has wheel & tyre info (restrictions)

http://www.transport.qld.gov.au/qt/LTAS ... an05v2.pdf

rnbboi · Post by **rnbboi** » Wed Nov 08, 2006 6:00 pm

its all good.

after some research and spoken to a few people, everything has indicated that the load limit should not be minimised on the car as like everyone has said, it can be a danger to yourself and others.

however, u can use a tire that has a higher load limit.

and for those who would like to change their tire size and is afraid of the wrong kmph reading on their speedos, i suggest u to use the following site:

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

just convert the mph into kmph.

khunjeng · Post by **khunjeng** » Wed Nov 08, 2006 8:18 pm

just get 17s with some 45s ken...or 18s with 40s or 35s....will work out ok generally..

have u looked at actual tyre brands yet?