New wheels - MG-Rover.org Forums

roy_newell · 19-05-2003, 20:05

Thinking of buying new wheels, with the new wheels my rolling radius would be 4.6% higher meaning my speedo would be 4.6% too slow so when I was travelling 100, I would actually be going 104.6, does anybody think this is acceptable or not?

jon · 19-05-2003, 20:15

hey, your speedos 10% out anyway!!

Sop i guess it dont matter what size hoops, are they monster truck wheels?

roy_newell · 19-05-2003, 20:38

my speedos 10% out? how do u know that and is it 10% under speed or over?

jon · 19-05-2003, 20:42

No, its just that your speedo is actually just a rough guess at your speed.

so it probably wont make any difference unless you have a digital speedo!

G13SJC · 19-05-2003, 22:10

Thats why police cars have calibrated speedos.

Roy - your speedo will be out as soon as your tyres begin to wear as the rolling radius of the tyre will be slowly getting shorter.

Regards

Steve

roy_newell · 19-05-2003, 23:08

so you think going for the wheels would be a wise move, or at least not a stupid one

cosb6 · 20-05-2003, 08:47

4.6% is fine... also, as the new tyres are bigger, it'll make the arch gaps look a lot smaller....

It's perfectly acceptable.

SteveMaxwell · 20-05-2003, 19:32

Ill sell you some Mint 16" Hairpins if you like

Steve

Orion · 20-05-2003, 20:46

Quote:

my speedos 10% out? how do u know that and is it 10% under speed or over?

The law states that a speedometer my under-read by as much as 10%, but that it may not overread at all.

Thus all mannufacturers tend to make their speedometers under-read by a significant amount. It would simply cost too much to make them totally accurate.

If you're increasing the diameter enough give an error of 4.6%, you will probably just be making the speedo closer to being accurate...

...but that's quite a big difference - have you considered getting a tyre profile that doesn't increase the rolling radius as much?

Ice D · 20-05-2003, 22:03

what u shovin on 17"s?

roy_newell · 21-05-2003, 00:27

No just some 16" hairpins hopefully with 205/50r16
sod buying lower profile tyres, that would mean buying tyres on top when i should get them altogether.
judging by what people have said its just gonna make it more accurate, to be honest going through speed cameras, most people seem to go faster than me and i go through dead on the limit according to my speedo

Ice D · 21-05-2003, 15:59

mine are 16" as u can tell

G13SJC · 21-05-2003, 16:58

Roy,

Stick those 16's on with current tyres. They will be fine.

Dont worry too much about the rolling radius, you may just rack up miles slightly quicker and unless youve got a real low miler then dont worry.

Im running 195/50 R15 on my 220SLi which are cheaper than 185/55 R15. The original steel wheels fitted were 175/70 R14. This means that im 4% under the speed. So if i cover 100 miles on my speedo, ive only covered 96 miles actual.

The saving on the tyres outweighs the extra miles i put on. Oh and i wont sell my car, ill run it into the ground!! (Like my previous maxi, maestro, montego, and 214)

Best Regards and hope you do get the 16's

Steve

Gavt_t · 21-05-2003, 18:20

Ive got 16's on my 25 with 205/50 on.

When i was at pod sunday my speedo was showing just under 75mph as i crossed the line and on my timing sheet my speed was 73.7mph.

Pretty spot on i think!

Gav.

roy_newell · 22-05-2003, 00:29

Well thats the same tyre as I'll have, so what was ure cars standard size?
by the way guys, I am getting them on friday, can't wait, god bless hairpins

Gavt_t · 22-05-2003, 08:52

It ran the nasty standard steelies with 175/64/14's before with 16's.
Think yours will be the same????

Gav.

roy_newell · 22-05-2003, 10:54

Sweet, the difference from ure old to new is 4.8% and mine will only be 4.6% so I think mine should be pretty spot on after, nice 1

SteveMaxwell · 22-05-2003, 10:58

Clicky Clicky

HTH

Steve

roy_newell · 22-05-2003, 14:12

Got the pic now mate, looks loverly, canny wait till tomorra, cya then

cosb6 · 22-05-2003, 14:32

Quote:

Originally posted by G13SJC

Stick those 16's on with current tyres. They will be fine.

Dont worry too much about the rolling radius, you may just rack up miles slightly quicker and unless youve got a real low miler then dont worry.

You'll actually rack up miles slower... so that's a bonus...

As for "speedos must read under" this might be the law for the manufacturer, but isn't the law for MOT's...

You don't even need to have a working speedo to pass an MOT. All you need is "a device for calculating the speed of the vehicle" and a Rev counter does this satisfactorily.

19-05-2003, 20:05	#1
roy_newell Registered User Join Date: Dec 2002 Location: Bristol Car: Rover 200 Coupe Posts: 3,287	New wheels (Help me I'm scared) Thinking of buying new wheels, with the new wheels my rolling radius would be 4.6% higher meaning my speedo would be 4.6% too slow so when I was travelling 100, I would actually be going 104.6, does anybody think this is acceptable or not? Last edited by roy_newell; 22-05-2003 at 16:27.

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19-05-2003, 20:15	#2
jon Registered User Join Date: Oct 2002 Location: back in london Car: Rover 200 (95-99) "Bubble Shape" Posts: 458	hey, your speedos 10% out anyway!! Sop i guess it dont matter what size hoops, are they monster truck wheels?

19-05-2003, 20:38	#3
roy_newell Registered User Join Date: Dec 2002 Location: Bristol Car: Rover 200 Coupe Posts: 3,287	my speedos 10% out? how do u know that and is it 10% under speed or over?

19-05-2003, 20:42	#4
jon Registered User Join Date: Oct 2002 Location: back in london Car: Rover 200 (95-99) "Bubble Shape" Posts: 458	No, its just that your speedo is actually just a rough guess at your speed. so it probably wont make any difference unless you have a digital speedo!

19-05-2003, 22:10	#5
G13SJC Registered User Join Date: Jan 2003 Location: Nuneaton Car: BMW E90 Posts: 1,817	Thats why police cars have calibrated speedos. Roy - your speedo will be out as soon as your tyres begin to wear as the rolling radius of the tyre will be slowly getting shorter. Regards Steve

19-05-2003, 23:08	#6
roy_newell Registered User Join Date: Dec 2002 Location: Bristol Car: Rover 200 Coupe Posts: 3,287	so you think going for the wheels would be a wise move, or at least not a stupid one

20-05-2003, 08:47	#7
cosb6 Registered User Join Date: Jun 2002 Location: Melton Mowbray (land of Pork Pies) Car: MG ZR Posts: 8,242	4.6% is fine... also, as the new tyres are bigger, it'll make the arch gaps look a lot smaller.... It's perfectly acceptable.

20-05-2003, 19:32	#8
SteveMaxwell Registered User Join Date: Aug 2002 Location: Staffs. Car: Other Manufacturer Posts: 148	Ill sell you some Mint 16" Hairpins if you like Steve

20-05-2003, 22:03	#10
Ice D Registered User Join Date: Mar 2003 Location: Bergen, Germany Car: Jaguar X-Type 3.0L v6 SE Auto Estate Posts: 5,355	what u shovin on 17"s?

21-05-2003, 00:27	#11
roy_newell Registered User Join Date: Dec 2002 Location: Bristol Car: Rover 200 Coupe Posts: 3,287	No just some 16" hairpins hopefully with 205/50r16 sod buying lower profile tyres, that would mean buying tyres on top when i should get them altogether. judging by what people have said its just gonna make it more accurate, to be honest going through speed cameras, most people seem to go faster than me and i go through dead on the limit according to my speedo

21-05-2003, 15:59	#12
Ice D Registered User Join Date: Mar 2003 Location: Bergen, Germany Car: Jaguar X-Type 3.0L v6 SE Auto Estate Posts: 5,355	mine are 16" as u can tell

21-05-2003, 16:58	#13
G13SJC Registered User Join Date: Jan 2003 Location: Nuneaton Car: BMW E90 Posts: 1,817	Roy, Stick those 16's on with current tyres. They will be fine. Dont worry too much about the rolling radius, you may just rack up miles slightly quicker and unless youve got a real low miler then dont worry. Im running 195/50 R15 on my 220SLi which are cheaper than 185/55 R15. The original steel wheels fitted were 175/70 R14. This means that im 4% under the speed. So if i cover 100 miles on my speedo, ive only covered 96 miles actual. The saving on the tyres outweighs the extra miles i put on. Oh and i wont sell my car, ill run it into the ground!! (Like my previous maxi, maestro, montego, and 214) Best Regards and hope you do get the 16's Steve

21-05-2003, 18:20	#14
Gavt_t Registered User Join Date: Oct 2002 Car: Other Manufacturer Posts: 125	Ive got 16's on my 25 with 205/50 on. When i was at pod sunday my speedo was showing just under 75mph as i crossed the line and on my timing sheet my speed was 73.7mph. Pretty spot on i think! Gav.

22-05-2003, 00:29	#15
roy_newell Registered User Join Date: Dec 2002 Location: Bristol Car: Rover 200 Coupe Posts: 3,287	Well thats the same tyre as I'll have, so what was ure cars standard size? by the way guys, I am getting them on friday, can't wait, god bless hairpins

22-05-2003, 08:52	#16
Gavt_t Registered User Join Date: Oct 2002 Car: Other Manufacturer Posts: 125	It ran the nasty standard steelies with 175/64/14's before with 16's. Think yours will be the same???? Gav.

22-05-2003, 10:54	#17
roy_newell Registered User Join Date: Dec 2002 Location: Bristol Car: Rover 200 Coupe Posts: 3,287	Sweet, the difference from ure old to new is 4.8% and mine will only be 4.6% so I think mine should be pretty spot on after, nice 1

22-05-2003, 10:58	#18
SteveMaxwell Registered User Join Date: Aug 2002 Location: Staffs. Car: Other Manufacturer Posts: 148	Clicky Clicky HTH Steve

22-05-2003, 14:12	#19
roy_newell Registered User Join Date: Dec 2002 Location: Bristol Car: Rover 200 Coupe Posts: 3,287	Got the pic now mate, looks loverly, canny wait till tomorra, cya then

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