Tyre width differences
Discussion
So, here is one for any tyre experts.
My wife's car has 205 45 16 tyres as standard. To improve the ride and economy I was going to go up to 205 50 16s. I went to my local place and when they put a 205 50 on to the rim, the sidewall of tyre was almost rubbing on the arch whereas with the 205 45 there was enough space to easily get my hand between the wheel and the arch.
So are larger profile tyres also wider for the same quoted width?
Or will manufacturers use the same carcass for 205 & wider tyres so a 205 actually ends up being wider?
My wife's car has 205 45 16 tyres as standard. To improve the ride and economy I was going to go up to 205 50 16s. I went to my local place and when they put a 205 50 on to the rim, the sidewall of tyre was almost rubbing on the arch whereas with the 205 45 there was enough space to easily get my hand between the wheel and the arch.
So are larger profile tyres also wider for the same quoted width?
Or will manufacturers use the same carcass for 205 & wider tyres so a 205 actually ends up being wider?
Even the same nominal size can be different. A while back I ordered some Vredestein Sessantas in 225/45-18. When they arrived I placed them next to the Bridgestone RE030's that I was replacing, and the Vreds were quite noticeably wider. The shape of the shoulder was quite different as well. Plenty of opportunity to have one tyre clearing the suspension and another rubbing if it is close.
(The Sessantas did fit, but the spring perch was very close to the sidewall). Much better tyres though.
(The Sessantas did fit, but the spring perch was very close to the sidewall). Much better tyres though.
Devil2575 said:
Err, it's a bigger tyre so no longer fits under the arch properly. It's 2 cm greater in diameter than the standard tyre. You've also increased the rolling radius so made the speedometer read low putting you at risk of points and a fine.
And effectively upped the overall gear ratio between engine and wheels. Buggers up the acceleration somewhat, and it will run out of steam on steepish hills in top gear as well.
. the difference in diameter should be 20.5 mm. The power of red wine..
It's not the top of the tyre that is nearly touching the top of the arch - it's the side wall on the side of the arch. It did look like it bulged a lot more than other tyres but I went back to 205 / 45 so no issues.
As for the gearing & acceleration the car is horribly undergeared anyway. 70mph is about 3,500rpm so not a nice place for a long cruise. It feels like the gearbox & final drive were spec'd for the 1.6 petrol and when they dropped in the 2.0 petrol they didn't do any work on the gear ratios.
It is also quite crashy so was hoping for smoother ride.
As for the gearing & acceleration the car is horribly undergeared anyway. 70mph is about 3,500rpm so not a nice place for a long cruise. It feels like the gearbox & final drive were spec'd for the 1.6 petrol and when they dropped in the 2.0 petrol they didn't do any work on the gear ratios.
It is also quite crashy so was hoping for smoother ride.
Devil2575 said:
Err, it's a bigger tyre so no longer fits under the arch properly. It's 2 cm greater in diameter than the standard tyre. You've also increased the rolling radius so made the speedometer read low putting you at risk of points and a fine.
It's not about the height of the tyre - it was about the width of the tyre. The tyre cleared at the top of the arch but not at the side of it and was much closer to the suspensionWell since the speedo overreads anyway it would have put it close to being accurate!
stavers said:
It's not about the height of the tyre - it was about the width of the tyre. The tyre cleared at the top of the arch but not at the side of it and was much closer to the suspension
Well since the speedo overreads anyway it would have put it close to being accurate!
Without seeing a picture of the old and new tyres it's difficult to comment.Well since the speedo overreads anyway it would have put it close to being accurate!
On the second point, it's your license
stavers said:
So, here is one for any tyre experts.
My wife's car has 205 45 16 tyres as standard. To improve the ride and economy I was going to go up to 205 50 16s. I went to my local place and when they put a 205 50 on to the rim, the sidewall of tyre was almost rubbing on the arch whereas with the 205 45 there was enough space to easily get my hand between the wheel and the arch.
So are larger profile tyres also wider for the same quoted width?
Or will manufacturers use the same carcass for 205 & wider tyres so a 205 actually ends up being wider?
Do higher profile tyres improve economy ? My wife's car has 205 45 16 tyres as standard. To improve the ride and economy I was going to go up to 205 50 16s. I went to my local place and when they put a 205 50 on to the rim, the sidewall of tyre was almost rubbing on the arch whereas with the 205 45 there was enough space to easily get my hand between the wheel and the arch.
So are larger profile tyres also wider for the same quoted width?
Or will manufacturers use the same carcass for 205 & wider tyres so a 205 actually ends up being wider?
Basic physics suggests not - any side wall flex will result in heat and so consume energy, but I appreciate the real world isn't always so easy to model.
Devil2575 said:
Err, it's a bigger tyre so no longer fits under the arch properly. It's 2 cm greater in diameter than the standard tyre. You've also increased the rolling radius so made the speedometer read low putting you at risk of points and a fine.
But most speedos are set up to overread, as they must given production tolerances and the fact that it is illegal for them to underread, so the chances are that fitting slightly higher profile tyres will reduce the overread slightly.stavers said:
So, here is one for any tyre experts.
My wife's car has 205 45 16 tyres as standard. To improve the ride and economy I was going to go up to 205 50 16s. I went to my local place and when they put a 205 50 on to the rim, the sidewall of tyre was almost rubbing on the arch whereas with the 205 45 there was enough space to easily get my hand between the wheel and the arch.
You're not going to improve economy like that and if you want to improve the ride you'll need to go for smaller wheels and larger tyres to keep the aspect ratio the same. You may not even improve the ride as I'm sure the manufacture has set the car's geometry and suspension up for the tyres they fit as original.My wife's car has 205 45 16 tyres as standard. To improve the ride and economy I was going to go up to 205 50 16s. I went to my local place and when they put a 205 50 on to the rim, the sidewall of tyre was almost rubbing on the arch whereas with the 205 45 there was enough space to easily get my hand between the wheel and the arch.
balls-out said:
stavers said:
So, here is one for any tyre experts.
My wife's car has 205 45 16 tyres as standard. To improve the ride and economy I was going to go up to 205 50 16s. I went to my local place and when they put a 205 50 on to the rim, the sidewall of tyre was almost rubbing on the arch whereas with the 205 45 there was enough space to easily get my hand between the wheel and the arch.
So are larger profile tyres also wider for the same quoted width?
Or will manufacturers use the same carcass for 205 & wider tyres so a 205 actually ends up being wider?
Do higher profile tyres improve economy ? My wife's car has 205 45 16 tyres as standard. To improve the ride and economy I was going to go up to 205 50 16s. I went to my local place and when they put a 205 50 on to the rim, the sidewall of tyre was almost rubbing on the arch whereas with the 205 45 there was enough space to easily get my hand between the wheel and the arch.
So are larger profile tyres also wider for the same quoted width?
Or will manufacturers use the same carcass for 205 & wider tyres so a 205 actually ends up being wider?
Basic physics suggests not - any side wall flex will result in heat and so consume energy, but I appreciate the real world isn't always so easy to model.
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