Tyre Pressure For The Yaris T-Sport

[Johan007]

Hi I don't have the manual for my mk1 (2001) Yaris T-Sport and there is no info inside the door frame. Anyone Know?

[alfiejts]

Have you looked inside the lower glovebox? That's where the label probably is....

[Raeman]

According to my owners manual, the tyre pressures are....

Front (2 passengers) 31psi

Rear (2 passengers) 28psi

That's for 195/50/15 tyre size which is the same size and fitment as the T-Sport.

[minidoughty]

That's for 195/50/15 tyre size which is the same size and fitment as the T-Sport.

no it's not. the tsport is 185/55/R15 standard, but most people do fit the 195's as they are better.

[wastedagen]

I have 195/50/R16 in my Yaris SR and I have put Front 35psi, and rears 33psi.

Regards

[Raeman]

That's for 195/50/15 tyre size which is the same size and fitment as the T-Sport.

no it's not. the tsport is 185/55/R15 standard, but most people do fit the 195's as they are better.

So why would Toyota put thinner tyres on a sportier car with 20bhp more than mine then??

Regardless of that, the pressure's should still be the same....Or am i going to get shot down by Mr pedantic again?

[minidoughty]

So why would Toyota put thinner tyres on a sportier car with 20bhp more than mine then??

Regardless of that, the pressure's should still be the same....Or am i going to get shot down by Mr pedantic again?

Haven't a clue... but the Tsport wheels are narrower than the SR one's (I owned a '99 SR for 5 years and a Tsport for 3 years) 1st thing i did was put the larger tyre on the Tsport.

Anyway back to the topic. That sounds about right for the tyre pressures,think the Tsport pressure was only 1 psi higher than the SR.

[Johan007]

Thanks it is indeed inside the glove box. 30psi and 29psi for 2 people.

Secondly the tyres size makes no difference to the pressure as Raeman pointed out. Basic GCSE science I think... the only thing that effects the required pressure is weight of the car. The T-Sport seems well balanced with only 1psi required in the front as my fat fronted Auris Diesel requires 6 more PSI in the front.

Thirdly in replay to why would Toyota put smaller skinny tyres on a powerful car is why not because it does look better with them and they will be easier to get up to temperature. Tyres are complicated topic and more powerful cars have bigger wider low profile wheels simply for looks and nothing more. Yes formula one cars have wide tyres but that is to do with cooling and making them last longer so not the same as road driving.

[Raeman]

Johan, i think the main reason for bigger wheels on powerfull cars is because of the disc brake sizes?

Take a look at an Audi RS4 or RS6, big BMW's and the like and look at the size of the front discs! That's why they need bigger wheels. B)

I will admit that 17" wheels on small cars, IE corsa's, saxo's and the like look totally stupid and do absolutely nothing for the handling.

I know this because i once owned a MK3 Golf Gti then i totally ruined the ride fitting 17" wheels and lowering springs! It made a bad car even worse but the less said about VW's the better imo!

Even the Yaris with 17"s look ridiculous apart from the new ones.

Minidoughty.....Sorry for the pedantic! ;)

[Johan007]

Johan, i think the main reason for bigger wheels on powerfull cars is because of the disc brake sizes?

Yeah this would be true... but again big brakes look good. Did you see the Top Gear episode when tried to improve a car through modifications... when new wheels and brakes are added the car actually clocked a slower lap time!

Interesting topic though. If you look at wide tyres like a Porsche they add them because they want the car to look powerful and wider tyres mean more contact patch to get all the power down and off the line quicker.... right?... actually wrong, basic Science means the contact patch of Porsche Tyres are the same as if the car had Aygo skinny tyres the difference being the shape of the contact changes but the surface area is the same.

@Raeman going off topic how many revs are you doing in your SR at 70mph in 5th?

[Raeman]

@Raeman going off topic how many revs are you doing in your SR at 70mph in 5th? (Quote Johan)

I'll find out for you tommorow. can't remember off hand though, been a while since i was last on the M/Way in the Yaris.

[alfiejts]

Secondly the tyres size makes no difference to the pressure as Raeman pointed out. Basic GCSE science I think... the only thing that effects the required pressure is weight of the car. The T-Sport seems well balanced with only 1psi required in the front as my fat fronted Auris Diesel requires 6 more PSI in the front.

I understand the logic in saying that weight is a major factor in tyre pressures, but its not the only factor.

Both Toyota and Audi quote different pressures for the same car depending on the size of the wheel. Now I'm not an engineer, but my suspicion is that the bigger the wheel, the shallower the tyre sidewall, then the wider the tyre is relative to the sidewall and more pressure is required to support the centre of the tread...

For the 1.0 Yaris, our 2008 manual says that the front pressure goes up by 3psi when you move from a 14" wheel to a 15" wheel (32 to 35). Its the same engine and therefore same weight, so there must be some other reason to justify the 3psi increase... Interestingly though, the rear pressure stays the same on both 14" or 15" wheels...

A general trend seems to be the lower the sidewall profile, the higher the pressure - even on the same car.

Back in the old days with "80" profie standard tyres, pressures used to be in the 25-30 range for most cars. Now (with lower profile tyres) they seems to be all in the 30s.

My A3 with 225 - 40 profile tyres needs 38psi in it - which is an awful lot - and much more than other models with 16" wheels and taller tyres...

Hmmm...

[Johan007]

Both Toyota and Audi quote different pressures for the same car depending on the size of the wheel.

Hmmm... yes well thats me and my GCSE's blown out the water. Your probably right and it is something to do with needing to support the shape or side walls.

[alfiejts]

To confuse things even more - even Audi can't decide....

On my 2004 A3 car, it specifically states that for this particular model (2wd, 2.0TDI engine, 3 door, 18" wheels, 225/40 tyres), the pressures should be 33psi front, 30 psi rear.

On newer 2009 cars of exactly the same model & spec, it now says 38psi front 33 psi rear.

Apart from the passing of time and five years of experience, nothing has changed. Perhaps its not an exact science for anyone....

[Johan007]

On newer 2009 cars of exactly the same model & spec, it now says 38psi front 33 psi rear.

I maybe able to explain that. It is typical of Diesels to ware the outside edges of front tires allot and this will help prevent that from happening. Many of Auris D's are running 38-44psi in the front though the book says 32-35 I think.