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MG MGB Technical - Wheel and Tyre sizes
|Apologies if this subject has been covered before, but I have searched the archives and haven't found it.|
I have 14 x 4.5 inch wire wheels on my 1972 GT. I am struggling to find decent tyres to fit them.
Does any one have any suggestions for a brand & size that is currently available and performs well, all I can find are light van tyres or the Vredenstein Classic.
Also can anyone clarify if it is ok to use tubeless tyres with inner tubes, some tyre fitters will fit them and some won't!
Thanks in advance for any assistance.
Generally speaking, you should be able to come up with something that is superior in all categories to the old P185/70R14 designs. Why do not more people continue to use them on their MGBs? Because when the original size tires became harder and harder to find, people switched to the P185/70R14 because they were more modern and they were what was available at the time that was closest to the original rolling radius. Since then it has become something of an Urban Myth that they are the best way to go. Actually, the more modern P185/65R14 is superior on almost every count and is in no way inferior to the older design. Unless you are substantially uprating the power output of your engine or modifying the suspension so you can drive very, very hard on curves, you do not need to go much larger. For most people, the P185/65R14 will do fine.
Beware of tubes that are labeled “radial / bias ply”. These one-size-fits-all tubes that are available at most modern tire shops simply will not work in our cars. By all means, use tubes that are intended solely for use in radial tires. Be sure to check the inside of your tire for a little square information block. Some tires have this and it will scrape on the tube, so it should be removed. Run a nylon stocking around the inside of the tire in order to assure there are no fine burrs or anything that might cause wear of the tube. Here is an ol’-timey-mechanic's tip: dust the inside of the tire and the exterior of the tube heavily with talcum powder. The stuff will act as a dry lubricant for reducing chafing. If you can, find an unscented product as the perfumes might have some effect on the rubber. Perfume in talcum powder rots rubber, which is why divers never use it on their wet suits. Unscented talcum powder is sometimes called “French chalk,” so you might find it under that name as well. It also helps to “burp” the tire after it has been inflated to seat the tire bead. Once the inner tube has been inflated and the tire bead is seated, remove the valve stem core and let the pressure out of the tube. Move the valve stem around (gently) while it is deflating. This lets any air out that is trapped between the tube and tire, causing a bubble. Repeat this process until no more air escapes around the valve stem.
I have recently replaced the 165R14 Michelins (1986 installation) on my roadster with 175/75R14s by Bridgestone, a locally made tyre. Car tyre, not van, sedate sedan type tyre which suites my car use which is day driver and occasional tourer. Based on my research at the time these were the next nearest to the 165R14s in diameter in the local market after 185/70r14s. Very close to the 165r14s.
I have seen photos of 175/70R14s on the B. I think they look just too small a diameter. Others have said that 185/70R14s, whilst nearest to the original 165R14s in diameter, look like donuts on the 4.5 inch B wires. I do know that here there are tyre manufacturers who debar 185s on 4.5 inch rims - specifying a minimum of 5 inches for that width of tyre. I think there would be issues of wall flex with the 4.5 inch rim. Having said that, they are used by many on the 4.5 inch wire rim and they are available.
I wonder whether the 185/65R14 tyre may also look a little small in diameter? Again, it may be a more available size and a 'look' which we will all eventually have to adapt to.
Personally, I would pick a tyre which I liked and which fitted my car use and worry about speedo accuracy afterwards. After 30-40 years not many unmolested speedos are going to be anywhere near accurate. If strict accuracy is an important issue for you, I suggest pick your tyre and then have your speedo calibrated to that fitment.
|I've been running tubes in tubeless tyres on wire wheels for 25 years without a problem.|
The original radial tyre was 155/80 for roadsters and 165/80 for GTs. The latter causes the speedo to under-read by 2.7%, let's hope the speedo over-reads by more than that. 175/70 should be commonly available in the UK and are almost identical speedo-wise to the 155/80.
|Stephen, Roger & Paul.|
Thanks for the information, its very helpful.
I'll go for the 175/75's I reckon, there is quite a choice and it shouldn't be hard to source.
Speedo is pretty accurate at the minute (according to my GPS) so I'll be able to work out the difference once I fit the new tyres.
I have owned MG's for about 15 years now. Its only recently that I have been having problems with tyre fitters not wanting to put tubes in tyres or not wanting to touch wire wheels at all.
Next mission to find someone to balance the wire wheels as this seems to be increasingly a rare skill. I had to show the incredulous mechanics how to remove the spinners and wheels last time I went to get it done, they had never seen them before, needless to say my wheels were still wobbly when I left.
Thanks again for the advice.
|Tire Rack show 185/70R14 as the default tire for MGBs, FWIW.|
I have had great performance on my 1967 MGB with the OEM Dunlop wire wheels and Michelin 175R-14 rain force radials, but after 15 years; age has finished them off. I just mounted my Dayton Chrome wires with Vredenstein 175R-14. Great ride, and probadly one of the last tire manufactures producing non profiled tires. It should be noted; with Daytons; no tubes are required.
Rich Boris 67 MGB
|I should have added that I have radial tubes sized for the 175/75 tyre. No problem getting them fitted with the tyres, though I use a supplier well versed in classic wheel/tyre fitting issues.|
|Conventional balancers hold the wheels by the wrong surfaces, I've had the fitters show me a massive wobble on the machine that simply isn't there on the hub, so I've usually left them unbalanced. I started looking into balancing cones a while ago and got a pair made, and coincidentally bought a pair of new rear tyres that were so unbalanced that I could feel the back of the car bouncing up and down. The fitters were very obliging and assessed the weights that were required both with their cones and mine, and there was a significant difference. Balanced with mine even on the front they are steady as a rock, whereas before the vibration was terrible. Several other people were interested in getting a set of these cones but unfortunately the machinist didn't want to make any more for some reason.|
Thanks for your post, I have heard about getting cones made before. I also have had an issue with a brand new wheel having a huge wobble that just wasn't there on the car.
Do you have drawings or dimensions of those cones? My tyre fitter is being very helpful, but is inexperienced with wire wheels, I have hunted about and short of finding someone who knows exactly what to do, I'm prepared to go along the route of showing him.
I have some connections in the engineering industry in the NE so I might be able to find someones arm to twist to make them. If I can get a few sets made I'll make them available to those interested.
|I just had a set of General Altimax 175/70R-14 tires mounted on a set of Minator knockoff alloys. They have an aggressive tread pattern and are reasonably priced. So far, I am very pleased with their look and performance. Having been machined on the inside of the wheel, the standard balancer cones work perfectly with these wheels. They replaced a set of Michelin 175/70R-14 tires and Dayton chrome wire wheels that rusted out after 10 years. RAY|
|Ok I have found the drawings for the cones, I'll get some made up and see what happens, I'll post the results on here when its been done, give me a few weeks though as I am out of country on business.|
|I've just purchased a set of KN Minator wheels fitted with Avon 175/70R14 tyres, however I find that the nearside (RHD) rear tyre fouls the lip on the wheel arch. The car is a '73 chrome bumper car with the typical slightly-offset rear axle. |
My original RoStyles are fitted with 165/80R14 don't foul the arch.
I'd like to use the Minators, the Rostyles have rusted on the inside and I keep getting slow punctures in the tubes.
What's the best option, grind back the arch slightly, stick with 165 profile tyres or is it possible to correct the axle offset? In the short time I drove the car with the 175/70R tyres the handling did appear to be a lot more sure-footed, but maybe that's due to a different tyre compound.
|If anyone in the (UK) Midlands want to try and get a set from the chap who did mine be my guest, he has the drawings: Brian Dickens, B & M Engineering Services, 6 Rowan Court, Crystal Drive, Smethwick, B66 1RB, 0121 541 1216.|
|Current european 165/80R14 tyres:|
Uniroyal Rallye 380
Of these tyres I think the Uniroyal looks best on the MGB.
|Willem vd Veer|
|Mike, 175s are only marginally wider than the stock tires, so I would try to grind a bit off the inside of the wheel arch. I almost went for 185s when purchasing the new wheels and tires but stuck with 175s because I have had no rubbing issues with them in the past and wasn't willing to press my luck by going 10mm wider. The 175s grip the road very well, in my experience. RAY|
|Thanks Ray, I ground back a bit off the wheel arch this morning, most of the rubbing problem was cause by a couple of messy welds left over from a previous lower ring replacement. The wheel rubbing is now almost gone and only rubs when I hit largish bumps at fairly high speed. Another couple of mm ground off and they should (just) about be clear.|
So far I'm surprised at how much different these wheels are over the RoStyles, I no longer have to suffer an vibration when travelling at motorway speed. I don't know if it's my imagination, but there seems to be less road noise as well.
|Mike, I had to do the same thing some years ago after I got the car back from being restored. A little too much welding had to be ground down to allow clearance for the tires. I hope you enjoy the Minators, I'm quite pleased with mine. RAY|
|I've just been offered some Minators with 185/70 R14 tyres. Is there some possibility of these fouling the arch of my '68 roadster? (see my recent thread). I though 185s were common enough. Am I likely to run into trouble? I don't yet have the correct rear axle yet as it's currently fitted with wires so I can't try them out.|
If the bushings of your rear springs are in good shape, you shouldn't have any problems with the sidewalls of the tires rubbing against the inner lip of the wheelwell unless you throw the car very hard around turns. If you tend to drive that way (it's a sports car, for crying out loud!), a Panhard rod will solve that problem, plus improve tracking as well.
This thread was discussed between 07/08/2010 and 11/08/2010
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