Tyre sizes again...

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Johnny 216GSi
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Tyre sizes again...

#1 Post by Johnny 216GSi » Sat Mar 30, 2019 7:24 pm

Right - 14" Rover cross-spoke alloys. Tyre size is 185/60/R14

What would be the issues (apart from incorrect gearing/speedo reading) with fitting 65% profile tyres, i.e. 185/64/R14?

I suppose (pre-emptively) - 6.5mm higher ride height and tyre roll on cornering - but does the extra % make them unsafe?
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RoverRevival
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Re: Tyre sizes again...

#2 Post by RoverRevival » Sat Mar 30, 2019 8:18 pm

would feel like driving a space hopper.

As for safety, no real difference. your still not going to touch the bodywork or anything, so as long as they are in date, you'll be fine.
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richard moss
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Re: Tyre sizes again...

#3 Post by richard moss » Sat Mar 30, 2019 8:30 pm

1234dist wrote:
Sat Mar 30, 2019 8:18 pm
would feel like driving a space hopper.
....or could be viewed as giving a decent ride quality at last.

I know that it made a noticeable difference (improvement) on our old 414 R8 when we stepped up a tyre size. It also looked better - the originals looked stupidly skinny

As for gearing, we went from a speedo that over read quite badly to it being just about spot on
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Julesmat50
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Re: Tyre sizes again...

#4 Post by Julesmat50 » Sun Mar 31, 2019 12:37 am

Johnny 216GSi wrote:
Sat Mar 30, 2019 7:24 pm
Right - 14" Rover cross-spoke alloys. Tyre size is 185/60/R14

What would be the issues (apart from incorrect gearing/speedo reading) with fitting 65% profile tyres, i.e. 185/64/R14?

I suppose (pre-emptively) - 6.5mm higher ride height and tyre roll on cornering - but does the extra % make them unsafe?
There are no real issues with fitting slightly higher profile tyres as others have mentioned, as long as the obvious "put identical sizes on each axle" is maintained. Even the speedo reading is not much different, about +3.2%, which means if your speedo reads 70mph, you are actually traveling at 72.24mph. However as most speedos are at least 5% and sometimes as much as the legal max of 10% incorrect (especially cable driven ones), you probably wouldn't notice. All that would really happen is that normally, speedos are set to deliberately over-read, so the inherent inaccuracy won't result in you actually speeding when you think you are traveling within the speed limit according to the speedos indication. By fitting slightly bigger tyres, you remove some of that over-read, so you are closer to the actual speed indicated. The rolling radius increases by about 55mm - so each revolution of the wheel will take you 5.5cm further than the old tyres did. :laughing2
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