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MG MGB Technical - 165/70R14 Tires
|Has anyone used 165/70R14 tires instead of the taller originally supplied 165R14's? Obviously these lower profile tires have a smaller outside diameter resulting in speedo error and higher revs. However, they go for about 1/2 the price of available 165R14's. |
Also would they look right compared to the taller 165R14's?
Here are some numbers I've gathered.
155R14. Supplied on early MGB's. 23.8" outside diameter which gives about 3311 rpm at 60 mph in a non-O/D gearbox. A Firestone model is available at Universal tire on-line. This is a lower cost tire than 165R14's. Tread is narrower than the options below.
165/70R14. 23.1" dia. which gives about 3400 rpm at 60 mph. Several internet suppliers. A local shop is one of their partner installers. Handling might not be bad as there is less sidewall flex on the 165/70R14 vs 165R14. Of course it depends on the tread and rubber even more.
165R14. Succeeded 155R14 as standard issue for many years. 24.5" dia. Revs are about 3225 rpm at 60 mph. Only sources I know are Vrederstein from Coker and others and a very expensive Michelin model.
My 65 has the original 4"x14" disc wheels. They wear old 165R14's that must be replaced this season.
General advice is not to exceed 165 width tires on these narrow rims. Of course, I could buy new wider wheels and go with more modern tires. But, I'm trying to keep costs down and stay reasonably stock. I don't do any spirited driving these days.
Lots of threads in the archives on this and many with helpful pics. Your car - your call, and answerable to nobody.
I would be concerned with the wheel-well appearance, particularly at the front. But that is just me. I replaced my 165R14s a couple of years ago and know the difficulties of finding replacement tyres. I went with 175/75s rather than 175/70s for the reason I stated. Mine are Goodyear, a local production, though now I believe discontinued.
Speedo issues can be separately addressed via recalibration, so in my view that should not be a driver to a decision.
I acknowledge the wisdom regarding 4" rims. I do think that is an important consideration that should be factored in.
My view, whatever suits for reasons that make it sensible for you.
Mentioned in archives lot of discussion about that. And late B had 185/70x14 from Co. If you used that tire size program:
165R14( read 165/82x14 yield to a difference of 6.75% on speed-o. If you don't have an OD you wont enjoy hi-rev. at 70 mph.
|Jean Guy Catford|
|I agonised over what size to get - so little choice here.|
I opted for 175/70 Pirellis in the end. They are on 4.5" wheels
|Robert I would stay with the 165/14, I don't think you would like the look of the smaller tire which is almost 1 1/2" less in diameter. I had the same problem several years ago and went with the Vredestein and were very happy with them. I later changed the wheels to wider ones which could take the 185/70 14 tires. |
|165/70 over-reads on the speedo the original roadster 155/80 by 2.7% so no problems there. I think you would have to look very carefully to notice the 8mm reduction in rolling radius. Incidentally the original GT 165/80 caused the speedo to *under*-read by 2/7%, but the speedo would have to have been almost spot-on to fall outside the 'can over-read by up to 10% but not under-read' original calibration limits. For whatever reason my V8 *is* almost spot-on. At the moment we have an unwritten rule that, for the most part, you can exceed the speed limit by 10% plus 2 mph before you get 'done'. But they are proposing upping the speed limit from 70 to 80 on motorways with legally binding (as opposed to advisory) variable speed limits, but you will be timed over a distance and there will be no leeway - 81 and you are done. There's a lot of fuss from the safety merchants over this proposal - all for 1 mph extra to all intents and purposes. But in fact speeds of 90 and above are common on motorways, so most car drivers will have to slow down!|
|Thanks so much for all the comments. As stated it's an owner decision. |
John, thanks for the image.
Andy, did you have to internet order your Vredersteins? I'm leaning that way.
Too bad the original wheels weren't 4-1/2". Then I could use 176/70's. When I got the car the DPO had one original rim and mismatched Datsun rims. All were wearing 185R14's. Talk about squirrely handling. The 185's were quite pinched in at the rim. I was lucky the beads didn't let go.
Jean, that was a handy calculator. I forgot the 165R14's were nominally about 82 profile. I used 80 in my calcs. So the increased revs are worse than I thought.
A 82 ratio for R was documented in many places like:
And at that time in america we had also odd ratios like 78 with a letter to complicate tires choices.
|Jean Guy Catford|
|I like the Vrederstein Sprint tires. I have them 175R-14|
mounted on Dayton Chrome wire wheels & tubeless. Nice riding tires; but not as good as the old Pirelli Cinurato's; which was like riding on chewing gum.
This thread was discussed between 06/04/2012 and 11/04/2012
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