Sorry, yet another tyre/wheel question Plus 2

PostPost by: NYK » Sun Mar 01, 2020 12:03 pm

I would like to use a wheel/tyre combination which is as close to the original diameter as the original tyre to minimise speedo error. Manual says the wheel/tyre was 5.5 J 165X13. Question is this the same (diameter) as a 165 80 13?

If yes, then it would seem that a 185 65 14 on a 6J would be very close with only a 0.4% reduction in diameter/circumference. As I have fitted the narrow rear springs this should fit without fouling anything.

Am I right, or am I wrong?
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PostPost by: nmauduit » Sun Mar 01, 2020 12:24 pm

a plus2 benefits from significantly more wheel arch room than 2 seaters, so the odds of a good fit are in your favour. 14" rims would likely allow for more room for the calipers as well, so all looks promising there, too, and narrow rear springs offer more clearance as well - yet one must still pay attention to backspace when departing from a known working solution (which is still subject to actual car assembly in some cases, e.g. left not being equivalent to right regarding tire clearance), esp. if a choice must be made based on calculations and not try fit.

ps: I know, I did not reply clearly to the original question...
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PostPost by: NYK » Sun Mar 01, 2020 12:34 pm

nmauduit wrote:a plus2 benefits from significantly more wheel arch room than 2 seaters, so the odds of a good fit are in your favour. 14" rims would likely allow for more room for the calipers as well, so all looks promising there, too, and narrow rear springs offer more clearance as well - yet one must still pay attention to backspace when departing from a known working solution (which is still subject to actual car assembly in some cases, e.g. left not being equivalent to right regarding tire clearance), esp. if a choice must be made based on calculations and not try fit.

ps: I know, I did not reply clearly to the original question...

Good point re backspace, I’m coming down in favour of one of the minilite designs, possibly using the Spydercars 14” offering.
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PostPost by: sprintsoft » Sun Mar 01, 2020 1:06 pm

NYK, this calculator should help you decide, it looks like you would have negligible effect on the speedo...

https://tiresize.com/calculator/

It shows that 165/80R13 has a circumference of 73.5" with revs per mile 863

and the 185/65R13 would be 73.7" with revs per mile 860

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PostPost by: NYK » Sun Mar 01, 2020 2:59 pm

sprintsoft wrote:NYK, this calculator should help you decide, it looks like you would have negligible effect on the speedo...

https://tiresize.com/calculator/

It shows that 165/80R13 has a circumference of 73.5" with revs per mile 863

and the 185/65R13 would be 73.7" with revs per mile 860

Iain

Thanks Ian, but I’m still not sure if the 5½J 165X13 is the same as a 165/80R13. The original specification from the manual does not give a height rating for the tyre, ie 80 and that figures clearly effects the diameter of the tyre (if I understand things correctly)
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PostPost by: sprintsoft » Sun Mar 01, 2020 4:08 pm

From memory the original tyres were 78 profile, so you could take 80 as the nearest equivalent nowadays
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PostPost by: NYK » Sun Mar 01, 2020 4:28 pm

sprintsoft wrote:From memory the original tyres were 78 profile, so you could take 80 as the nearest equivalent nowadays

Then I think that would make the 185/65 14 pretty close
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PostPost by: Citromike » Sun Mar 01, 2020 10:14 pm

Every tire brand/model height/ diameter is different - you can (should) refer to a tire dealer site online, such as Tire Rack, to locate actual sizes rather than relying on a theoretical calculator.

A pal of mine created an entire business that has sustained him for decades. You don’t know what fits until you try it (sadly). His book has proven fitment combinations, done by real tyre tire stores on real vehicles. It’s called the plussizingguide.com and sold mainly to tire dealers.

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PostPost by: wotsisname » Mon Mar 02, 2020 12:02 pm

In case you aren't aware - the original sizing is available again.. (£83 ea)
https://www.blockleytyre.com/product/165hr13

and of course the wheels are available again (possibly limited availability ?) from Sue Miller / TTR

I have no additional knowledge as to whether these are good tyres (grip, wear, etc)
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PostPost by: NYK » Mon Mar 02, 2020 12:10 pm

Thanks, useful info
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PostPost by: Spyder fan » Tue Mar 03, 2020 7:21 pm

I use 185/65/14 tyres on 14x6 Minilite style rims on my +2, the overall diameter of the tyres is near as can be to the original 82 profile tyres fitted to the 13 inch rims.

They fit the arches nicely too! You will need narrower springs on the rear to give clearance for 14x6 minilites if you do t already have them fitted.



2019-09-21 16.28.30.jpg and
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PostPost by: NYK » Tue Mar 03, 2020 7:40 pm

Spyder fan wrote:I use 185/65/14 tyres on 14x6 Minilite style rims on my +2, the overall diameter of the tyres is near as can be to the original 82 profile tyres fitted to the 13 inch rims.

They fit the arches nicely too! You will need narrower springs on the rear to give clearance for 14x6 minilites if you do t already have them fitted.



2019-09-21 16.28.30.jpg

Thanks, that confirms what I thought was the case and I have fitted the narrower springs so should OK
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PostPost by: NYK » Wed Mar 04, 2020 4:47 pm

Spyder fan wrote:I use 185/65/14 tyres on 14x6 Minilite style rims on my +2, the overall diameter of the tyres is near as can be to the original 82 profile tyres fitted to the 13 inch rims.

They fit the arches nicely too! You will need narrower springs on the rear to give clearance for 14x6 minilites if you do t already have them fitted.



2019-09-21 16.28.30.jpg

I’ve just ordered a set of 14X6 minilites from Spydercars they confirmed that the 185/65/14 tyre was as close to the original diameter as possible, but they did say that on some cars on full lock they can suffer from fouling of the tyre at the front. Have you noticed that problem?

I did wonder about fitting a 175/70/14, which again is very close to the original diameter but of course is that much narrower, has anyone tried this size of tyre?
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PostPost by: Spyder fan » Wed Mar 04, 2020 7:28 pm

The tyres can rub the inside of the wheel arches slightly on full lock. ( the trailing edge of the outside face of the tyres contact the inside rear of the wheel arch). There are slight witness marks on mine after 3 years, I don’t think it happens every time, it’s dependent on the manoeuvre, maybe turning full lock into a sloping driveway. I don’t consider it be a problem.
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