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sp250 tire size

Chris_R
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Re: sp250 tire size

Post by Chris_R »

An interesting and very useful spreadsheet. Shows that not all tyres are the same even for the same size designation.
peterbee wrote: Wed Apr 28, 2021 10:45 pm I have calculated mph at 1000rpm for various gearbox/tyre combinations.
For comparison you might consider adding the Blockley 550/15 tyre. It's actually the closest size to the original Dunlop 5.90 x 15 RS5 being only 5mm smaller in diameter.

Another factor is that it is not recommended to vary overall tyre diameter by more than 3% from the original specification which gives a range of 640mm - 680mm as ideal and you need to take into account tyre wear as well so one of the Blockley sizes would be outside that range once worn by more than 1mm.

peterbee
Posts: 71
Joined: Wed Oct 25, 2017 11:37 pm
Location: Dunfermline Scotland

Re: sp250 tire size

Post by peterbee »

The Blockley 550/15 is a crossply tyre. I attached the spreadsheet with RPM at 1000 not knowing whether the table would be read only or not. Enter whatever RPM you wish in the box and the table will update and this will be true for the other variables you change.

Ian Slade
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Re: sp250 tire size

Post by Ian Slade »

Since my last foray into tyre sizes it seems that the 175/80 r15 size is now available, this tyre is only 1mm in diameter wider than the original Dunlop 590R15 tyre but can only be fitted to rims 4.50" to 6", so not suitable for standard steel rims, you have a better choice with 5.50J TR6 wires
Last edited by Ian Slade on Fri Apr 30, 2021 4:38 pm, edited 1 time in total.
Owner since the 70's, Genghis is slightly to my left.

Martyn Ross
Posts: 64
Joined: Tue Feb 02, 2016 7:46 am

Re: sp250 tire size

Post by Martyn Ross »

Fitting Michelin XAS 165 15 tyres transformed the handling of my SP250. They 'aint cheap, but as most owners don't do high mileage in their Darts they'll last a long time - possibly even longer than the Firestone tyres that came with my car: there is a code moulded into the tyre wall which my tyre man looked at and told me they were over 20 years old. He said they'd never wear out, but on the downside have all the grip of a slug in a barrel of beer!

Ian Slade
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Re: sp250 tire size

Post by Ian Slade »

There are 4 numbers in an oval,the first two are the week number in the year the second two are the last two of the year I.e 2612 would be the 26th week or June in 2012. For some unknown reason they invariably are on the inside wall, with asymmetric tyre this can't be helped but I suspect it is something the trade likes to keep to themselves. Tyes age harden and can become quite lethal in the wet really 5 years is a good limit.
Owner since the 70's, Genghis is slightly to my left.

Chris_R
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Re: sp250 tire size

Post by Chris_R »

I think 5 years is a bit short. As far as I know the recommendation is to replace after 10 years.

Ian Slade
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Re: sp250 tire size

Post by Ian Slade »

Most caravan sites state 3 years, whether this is due to the fact many caravans use pressures up to 60 psi and they sit around for longer periods than a car may have something to do with the recommendation. In normal use a car tyre is long gone after 3 years normal use which equates to between 30 to 40 thousand miles, tyres are no longer built for retreading and the carcass is weaker than on a crossly tyre.
Owner since the 70's, Genghis is slightly to my left.

OttawaSP250
Posts: 25
Joined: Mon Jan 11, 2021 5:32 pm
Location: Ottawa, Ontario Canada

Re: sp250 tire size

Post by OttawaSP250 »

I am looking for tires here in Canada , I am adding the chrome wires to the car, what do people think of whitewalls ? I'm not sold on them

These were recommended :

https://kontiotyres.com/whitepaw-classic/

The 165/80/15 has a 2 3/4 inch Whitewall

Ian Slade
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Re: sp250 tire size

Post by Ian Slade »

The 165/80 r15 is undersized compared original, I personally found that size poor on road holding, but that was many years ago and went for 185 section, personally I would
look for a diameter as near to 25.62" and a section of no more than 185. 185/70R15 is not bad if you can't get 175/80r15. your speedo will be more accurate than the 165 section.
Tyre chart-3.pdf
(38.31 KiB) Downloaded 35 times
Owner since the 70's, Genghis is slightly to my left.

fireboss
Posts: 45
Joined: Wed Feb 24, 2016 10:20 pm
Location: Whitby, Ontario

Re: sp250 tire size

Post by fireboss »

Good day Ottawa, I live in Whitby and used the company listed below in the USA for my Vredestein Sprint tyres which were his recommendation.

My Dart has wire wheels.

Best regards, Bruce

Chris at Extension 776

Sales & Marketing Specialist
Tires By Web
800-576-1009 x776
Tiresbyweb@tiresbyweb.com
www.TiresByWeb.com

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