Tyres vs mpg

[DorinD]

Hello, knowledgeable people. 

 

It's my first post here and I am looking for some guidance.

Few days ago I hit the curb with my left wheel and I got instantly a flat tyre. I changed it with my small tyre untill the next day when I bought 4 new tyres ( they needed changing).

As soon as I start driving with my small wheel, I noticed a noise, quite strong, the same like when your break pads are worn out. My discs and pads were changed few weeks ago.

I checked any signs of heat on pads and disc after driving it for a while and they were normal. 

The next day I changed all 4 tyres and the noise diminished.  Now it is bearable. 

My problem is that I went from 63 mpg to 55-57 mpg and when I go downhill, if the hill isn't steep enough, my speed is decreasing, while before it was increased. 

I have to say that the tyres are the same size like before. The new ones are Bridgestone Turanza T005 driveguard ( extra load).

Have you ever drive with winter tyres on a very dry day? The exact noise I get now.

I find it hard to believe that this noise and the consumption increase has something to do with the new tyres ( I am writting this after more than 5 days after I changed them).

What can be causing the noise and somehow breaking on the wheels?

I went motorway, driving on 75 miles/hour on ECO mode and after 60 miles my consume was 50 mpg.

I would like your ideas about my concern. 

Thank you.

[DorinD]

I have driven this car for 50k+miles and I know something isn't as it was before.

Feels like it is a smooth break applied. My petrol engine is more active than before. And another thing I noticed: my EV mode can go up to 35miles/hour since the incident, where before was disengaging at 25miles/hour

[jcps001]

If your car is slowing down downhill without you appluing the brakes, most likely is a stuck brake pad and/or caliper. Have trustworthy shop check it out. The Turanzas T005 are one of the best choices for safe, economy tyres there is. Provided they are fault free, you're good on those. Check your brakes and also your wheel bearings.

[Roy124]

16 minutes ago, jcps001 said:

If your car is slowing down downhill without you appluing the brakes, most likely is a stuck brake pad and/or caliper.

Fine a flat, quiet, level road, drive about 30mph and loosely hold the steering wheel.  Does it pull to one side?  That might suggest a stuck brake.

[Talking Hoarse]

Just a thought - I presume that these new tyres are directional /asymetric etc as most are, and so have an arrow on sidewall to indicate correct rotation - are they all fitted the right way round?

[DorinD]

57 minutes ago, Roy124 said:

Fine a flat, quiet, level road, drive about 30mph and loosely hold the steering wheel.  Does it pull to one side?  That might suggest a stuck brake.

I tried this in the day I had the new tyres. All was good. I am thinking this might have something to do with the break pads, although there is no heating coming out of them even after few hours of driving. 

I drove yesterday on a downhill road where you expect to gain speed , the speedometer slowed, slowly, but slowed. 

I will get back to the service who changed the discs and pads few weeks ago. Can they jump if you hit a curb?

Thank you for your answers. 

[Roy124]

The slowing on the descent might be the effect of increased regenerative braking,  just a thought.

[jcps001]

Oh it's a hybrid? Didn't think of that... If it's a hybrid, slowing down a slope is normal.

[Roy124]

14 minutes ago, jcps001 said:

Oh it's a hybrid? Didn't think of that... If it's a hybrid, slowing down a slope is normal.

Actually thinking about it, in cruise control, as I crest a rise I get an overspeed warning.  The car soon slows to the set speed despite going downhill.  Without regenerative braking it would normally increase speed. 

I think also that after significant changes we have a heightened arousal checking that all is as before.

 

[Cyker]

Get the tracking/toe checked - If you hit a kerb hard enough to pop a tyre then it's likely the wheels are out of alignment and are causing extra drag (Although to be fair if you have low profile tyres it doesn't take much to pop them!)

[AndrueC]

New tyres do typically increase fuel consumption due to the larger radius and increased rolling resistance. Its normally only amounts to a couple of mpg though depending on how worn the previous tyres were and shouldn't noticeably impact the overall driving experience.

So it sounds like there is some other issue at play as others have posted.

[TonyHSD]

One important question , what where the previous tyres make, model, specifications? 
Different tyres can change your car drivability, efficiency and overall feel. What you have experienced after the change is typical for when changing summer to winter tyres sets. Lost in 3-5mpg also normal between different tyre brands, models etc. If you had fitted an extra load tyres on a car that does not require XL tyres these are the most common signs. 
If the change in how the car drives and reduced efficiency came straight after the tyre replacement then likely it’s from the tyres. You need to double check the pressures on cold, first thing in the morning and keep those close to the label on your door shuts., can do slightly above but not more. If 2.3 bar are required you can do 2.35 bar for example. 
For the brakes, you have to measure temperature on each disc after some drive, stop the car and go around each corner with infrared thermometer. Fronts should be between 20-30C° , rears 15-24C° at this time of the year. 
1-3C° difference between L and R sides. Anything outside these numbers will point towards issues with brakes. Also if you have binding brakes you will have vibrations at around 40mph, then 60mph and up to around 70mph. 
The best tyres for Toyota hybrids are summer touring tyres like Goodyear efficient grip performance 2.  I am on my 3rd set of these, 40-60k miles per set and I will never change to any other brand, so good rubber 🛞

[Bper]

Did you you damage the wheel as well if so it may be worth while checking by jacking the car up and holding top and bottom of the tyre and see if there is any play in the wheel. It's possible you may have damaged a bearing or steering joint.😄

[Cyker]

Ooh, good point to check the tyre pressures - If I forget to tell the service agent, my dealer always drops the tyre pressures to what they say on the door, which would be fine if I still had the 17" rims those pressures are for, but they're too low for 15" rims now on the car!!

 

[Roy124]

1 hour ago, Cyker said:

Ooh, good point to check the tyre pressures - If I forget to tell the service agent, my dealer always drops the tyre pressures to what they say on the door, which would be fine if I still had the 17" rims those pressures are for, but they're too low for 15" rims now on the car!!

 

New label needed?

[hubrad]

As Cyker said above, get your wheel, geometry and suspension checked out.. as soon as I read hit a kerb after which it was noisy, that was my first thought.

I have one axle of Turanza T005 and they're great. One of the best combination of wet grip and fuel efficiency available!