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MG MGB GT V8 Factory Originals Technical - Tire Sizes...Again!

Okay, I want to revisit this subject as I'm getting close to rolling the chassis to get calibration data for instruments....I want the largest 15" tire I can get on a 15"x6" wheel & still turn under stock fenders...Have learned the following:

Stock MGB tire of 175x70x14" is 23-1/2" in diameter

185x60x15 is 23-1/2" in diameter & 7.2" wide
195x55x15 is 23.4" in diameter & 7.87" wide
195x60x15 is 24.2" in diameter & 7.2" wide
205x50x15 is 23.1" in diameter & 8.66" wide
205x55x15 is 23.9" in diameter & 7.87" wide

Looks like 195x60x15" is the best choice; its close to original diameter (24.2" versus 23-1/2")...I'll have to recalibrate instruments anyway as I'm using V12 Jaguar clocks; am converting to Bilstein tube shocks w/dual exhaust & anti-tramp bars & am told stuffing all those under the chassis will affect tire width (?)...any thoughts about going larger? Say, 205x55x15"?
Anthony Barnhill

Scratch all the's what I've just learned that complicates things (at least in my simple mind):

185 tire is 7.28" wide
195 tire is 7.68" wide
205 tire is 8.07" wide

Compound that: 185x50x15=22.28" diameter
x55x15=23.07" "
x60x15=23.736" "
x65x15=24.464" "
195x50x15=22.68" "
x55x15=23.448" "
x60x15=24.216" "
x65x15=24.984" "
205x50x15=23.07" "
x55x15=23.877" "
x60x15=24.684" "
x65x15=25.491" "

And, stock MG 175x70x14 are 6.890" wide w/23.646" I the only one who's confused?

Looks like 195 is the safest width w/55 to 60 being best fit...

Does anyone have anything larger under a car that's been lowered to chrome bumper specs w/suspension mods I'm making?
Anthony Barnhill

I have 195/60s under my CB V8, on 15x6 rims. There's plenty of clearance (it's a C wire wheel axle w/bolt-on hubs) and you could easily go up to 205s without needing to flare the fenders. I have 1/4" spacers between the wheels and the hubs. The wheels have 22mm of offset.

(If you use a bolt-on axle, you would very likely need to flare the fenders even with 195/60s on a CB car.)

195s may fit OK on the axles, but what about the spare? One of the POs of my GT V-8 used 195s and the spare tire load floor barely closed with the spare in place. He would force it closed and hold it with the Dzus fasteners, resulting in a permanent crease in the Hardura covering on the underside of the load floor.

Of course, this would not be a problem on roadsters.

Paul Kile
Paul Kile

Paul...spare is the easy part...Nissan made a little 15" space saver spare that will bolt right up & fit in the boot....even smaller than the original 14" spare...& they're readily available in salvage yards, inexpensively i might add!
Anthony Barnhill


Simple. I increased the height of the rear deck in my GT by about 1/2" to allow for a full-size spare. This turned out to be a _great_ way to go, because the deck sits tightly on the tire and is firmly supported by the same. So easy to do, by adding strips of wood around the underside of the deck. Unless you specifically looked for it, you'd never notice. The only pain is, you have to get the Dzus fasteners lengthened -- which involves welding, etc. ... kind of ridicuous.

The space saver tires just don't allow sufficient ground clearance when mounted on the car! Note how low the V8 intermediate muffler sits! And they are just about as heavy as a full-size alloy racing wheel such as a Panasport. Plus, with a space saver on there your driving enjoyment goes down to zero. Nah, don't bother with space-savers.

Tony, save yourself a bit of headache..
go here
Sean Squires

If I am not mistaken, the 195, etc. refer to tread width. The cross sectional width (the widest part of the tire) will be greater.

Mark Marchbanks

Guys, thanks a lot but my dilema solved itself this afternoon when I went to pay homage to the "gods of my local foreign car salvage yard"...took my usual ofering of Mr's Coors & Budweiser &, as we were pontificating the problems of the world, the subject of my V8 project came up. I explained that I had test fitted a chrome bumper front suspension beam so I could sort out the rubber bumper steering rack mounting problems..mentioned that I was at a loss over which size tire to put on the mid-80's Nissan 200SZ 15"x6" wheels I had acquired...well, out came a set of Kuhmo P195/60R15 87H Ecsta HP4's that had just arrived on a wrecked Japanese sportscar (I know, that's an oxymoron!)with less than 5,000 on the clock....$50 & a couple more 6-packs later & they were mounted on my wheels!!! Check my website tomorrow; photos should be up.
Anthony Barnhill

Anthony, WAY TO GO BRO!! That is how I wish we could all get our set-ups...

I am going to shoot for the 205/50r15's..

Larry Embrey

Anthony what is your website address?
greg phillips

I have 205/60 15 yokohamas on 6" rims on MGC.
The lips have to be turned up on the rear arches (but it looks stock), and on very heavy cornering you
get a slight rub on the nearside arch because of the rear axle's slight offset. I suspect a panhard rod would prevent this.
195 60 15 should be fine !
Chris C.
Chris Cooper

Suggestion: Pick the tire brand & model first, then get the dimensions from the manufacturer for that specific model. The dimensions will vary between manufacturers and even tire models of the same brand. A 195/60 brand X may measure different than a 195/60 brand Y.

Sean...great site! added it to the links page of my can also help other guys! thanks!
Anthony Barnhill

I'd like to add my first hand experience! I just installed Panasport 15X6's with Dunlop SP8000 205/55ZR15's - incrediable is the only way to describe. Absolutely no problems with clearance, both steering response and ride comfort improved significantly (replaced 10 year old 165 / 14s, no suprise). It's a 77B with Rover 4.6L / BW T5 and stock rearend (for now). Suspension wise - I have uprated and lower springs (by 1", ride height at 13.5" - center of rear hub to fender lip), 4X's over shock valving and Ron Hopkingson front and rear roll bars (rear bar anchored to floor of trunk) and rearend is near dead centered. Don't know if any or all mods attribute to no clearance problems, but probably don't hurt. I should point out I do have a very slight wheel shimmy (between 35-50 mph) and need to double check wheels are balanced properly - did have alignment done and it may just be systemic with the much wider tire.

Steve LaGoy

This thread was discussed between 24/07/2000 and 27/07/2000

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