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Tyre Sizes
- Thread starter AndyMinto
- Start date
) and I am trying to work out what it should read.
JEZ 280ZX
Well-Known Forum User
Hi,
The facelift 280ZXs were listed as having 205/70-14 tyres on 6 spoke 14" rims or Denovo runflat tyres in the metric 200/65-370mm size.
The earlier pre-facelift cars had 195/70-14s on their Iron cross 14" wheels.I think the gearing was slightly altered on the later cars?
Here's a useful calculator to work out how much you're out.Simply enter your current size and then the original size...http://www.powerdog.com/tiresize.cgi
The facelift 280ZXs were listed as having 205/70-14 tyres on 6 spoke 14" rims or Denovo runflat tyres in the metric 200/65-370mm size.
The earlier pre-facelift cars had 195/70-14s on their Iron cross 14" wheels.I think the gearing was slightly altered on the later cars?
Here's a useful calculator to work out how much you're out.Simply enter your current size and then the original size...http://www.powerdog.com/tiresize.cgi
Last edited by a moderator:
Nigel Brook
Well-Known Forum User
Yes, but you're running 15" rims which should put you back to near standard rolling radius. It's the tyre profile ie, 60 or 70 series which is the deciding factor. I would suggest there's something else that's hurting your mpg.
Nigel Brook
Well-Known Forum User
If it's a bigger overall dia, and I'm not saying it is, (only a proper measurement will determine that), you will need more throttle (and hence more fuel) for a given rate of acceleration, but I would think it's marginal. I presume all the gearing is standard?
Last edited by a moderator:
AndyMinto
Inactive
Nigel,
Thanks for the info. I believe that the 60 or 70 bit is a ratio of the side wall height to the tread width. This means that, a Jez has pointed out, that I would have a larger diameter and hence circumferance. I am not sure about the gearing as I believe the car (MK2) has an american auto box. It is certainly smoother than the MK1 and shifts between massive ranges. Depending on load, it will shift from 2nd to 3rd at 2000 rpm to 5000 rpm (please see my post on Autobox Noise). Have you (or anyone on here) got any idea if the filters are the same across all of the autoboxes as I have a new one for the MK1?
By the way the car used to belong to the Insurance Valuation Officer Pete Parmenter. If anyone has any info on mods made to this car I'd be grateful for the info.
Thanks for the info. I believe that the 60 or 70 bit is a ratio of the side wall height to the tread width. This means that, a Jez has pointed out, that I would have a larger diameter and hence circumferance. I am not sure about the gearing as I believe the car (MK2) has an american auto box. It is certainly smoother than the MK1 and shifts between massive ranges. Depending on load, it will shift from 2nd to 3rd at 2000 rpm to 5000 rpm (please see my post on Autobox Noise). Have you (or anyone on here) got any idea if the filters are the same across all of the autoboxes as I have a new one for the MK1?
By the way the car used to belong to the Insurance Valuation Officer Pete Parmenter. If anyone has any info on mods made to this car I'd be grateful for the info.
JEZ 280ZX
Well-Known Forum User
Hi,
When you're doing 60mph your speedo will be reading 57mph compared to the stock 195/70r14 wheel/tyre...
Your wheels are turning 773 times per mile as opposed to 815 times for the 195/70r14 or 797 times for the 205/70r14s.
When the 195/70r14 wheel and tyre has completed 10,000 miles on the odometer, your odometer would only be reading 9481 miles!
When you're doing 60mph your speedo will be reading 57mph compared to the stock 195/70r14 wheel/tyre...
Your wheels are turning 773 times per mile as opposed to 815 times for the 195/70r14 or 797 times for the 205/70r14s.
When the 195/70r14 wheel and tyre has completed 10,000 miles on the odometer, your odometer would only be reading 9481 miles!