MG MGB and MGB GT Tech Talk
Ok, I've seen people say they run 175's and 185's. I'm currently running 175's but I think they may be smaller than what was originally on the wheels. What size tire came stock with our B's? I've been running on....old to say the least tires and I'm planning on replacing them either this week or next. I have the Rostyle wheels that came with the car (best of my knowledge) and 175/70R14's are on them.
Ned,
Size is pretty much a matter of individual preference and the direction you're going with your car. If you want strictly stock, go to the 165s as John said. If you want handling & a more modern look, the B will handle up to 195/60 x 15 wheels without body modifications.
Steve
Stephen said...." If you want handling & a more modern look, the B will handle up to 195/60 x 15 wheels without body modifications. "
True, but not on the Rostyle wheels!
A 185/70/14 is a nice upgrade in my opinion on stock Rostyles.
RS
Sorry to hijack this thread. I plan to replace my rostyle to a minilite 14x4.5. What is the lowest profile tire out there for this set up.
Dakine, get the 15" wheels if you can. Better tire selection and as Stephen said......." If you want handling & a more modern look, the B will handle up to 195/60 x 15 wheels without body modifications. " :thumbsup:
RS
Here's some info I posted on a previous thread.
Stock sizes (diameter)...
155R14 = 597.4mm = 23.5197"
165R14 = 613mm = 24.1339"
above based on an aspect ratio of 78.
Replacement sizes (diameter)...
175/65/14 = 583.1mm = 22.9567"
175/70/14 = 600.6mm = 23.6457"
185/70/14 = 614.6mm = 24.1969"
Wow, so if I upgrade to 185/70R14 I'll actually have more of a stock look? Either way I really do want to raise it up a bit and possibly get the speedometer in check. Is there a way to adjust the speedometer when I'm done or is it all mechanical and stuck where it is?
Check different tire sizes here (http://www.miata.net/garage/tirecalc.html). G
Check different tire sizes here (http://www.miata.net/garage/tirecalc.html). Good way to be sure your ride height and speedo calibration aren't adversely affected.
You dont really want to raise it up! The speedometer difference is not worth worrying about.
RS
What is the size of a 165R14 then? It doesn't give the second number.
165R14 is approximately equivlant to a 165/80R14. Generally speaking a lot of older tires were 80 series.
Try this http://www.mintylamb.co.uk/?page=tyre.htm
Fun to plug in any size you like. Probably like Rick's link
RS
I wouldnt buy 4.5 inch wide wheels.
Today's lower profile tires are better suited to a wider wheel, which will improve braking and handling.
5" wide wheels, as used on the MGB-GT, would be better, and 5.5 inch width wheels should fit without difficulty.
The wider widths should also be (pardon the pun) much more widely available.
Ned,
the 1972 roadsters were delivered with 155SR14 tyres on 4 1/2" wires or 5" Rostyles, while the GT always had 165SR14 tyres fitted to the same rims.
For your roadster, the 175/70 R 14T would have a nearly spot on circumfance compared to the original ones, so the speedo readings will not be negatively affected in any way.
Larger and wider tyres have been used on the B but they do not really have advantages, as long as no wider rims were choosen too! 185/70 on 5" rims do not give any real advantage over the 175 /70 concerning handling, roadholding and breaking.
Even when fitting larger and wider tyres on different rims to the car, it would only lower the mpg readings and increase wear on the suspension, as long as you do not invest in springs, dampers and bushings too.
Consider that when fitting larger wheels to an otherwise stock MGB, even when late ones were factory fitted with the 185/70's on alloy rims, but there were many changes to the suspension for the 1975 on modell done.
Ralph
I prefer the 14" - 185/70/14. Less unsprung weight than 15's and faster to spin up (we need all the help we can get!)
I even downsized from 18 to 16 on my Land Rover. Felt like I put a supercharger on it, it was a lot peppier (as a LR can be) not having to spin up something with the weight of a manhole cover!
One of the best bangs for the buck is a set of LE wheels. Look nice, cheap used, original lookingand light! Second choice would be ultralights or minilite replicas
Dakine,
I have 14" minilites with 195-60-14. Here's a photo of what that looks like.
Ned.
It's my opinion that the 175/70 is a tad smaller diameter than original design spec. This isn't a big deal, but it does increase engine revs at cruising speed which is an issue if you don't have overdrive. That's the big reason in my view to go with the taller tire. A secondary reason is improved ground clearance, as I like driving quickly, even over bumpy ground, sleeping policemen and rocks that seem to lie in wait around every canyon corner.
My personal preference is the 185/70 on the 5.0" Rostyle or 5.5" alloy wheel. You can go wider (I have) but there is not a lot of benefit as the steering design and limited suspension travel don't allow the wider footprint to really be useful on the street.
If you have the interest, here is an article I wrote on tire sizing that may be helpful.
http://www.mossmotors.com/graphics/products/PDF/Tire%20Sizes.pdf
Just so everyone understands I'm not an anti performance stick in the mud. I am planning on running big nasty 215/50-15 tires on 7" wheels on my V8 MGB. But that car has a whole lot of different reasoning built into it. Tire life, longevity and economy take a back seat to mid life "wanna".
kelvin
In my humble opinion, I love running the 175s, because, at least from my experience, most people don't push the car enough (at least in stock/near stock form) to overcome thier grip, but you still overcome them when you want to for some nice spinning/sliding action.
Ok, stupid question here. I'm used to the other tire measurements. When you say 175/70R14 what do all those numbers mean? I know the R14 is the rim size but the other two confuse the hell out of me.
Ok, I had to google this for 20 minutes to try and understand this. 175/70R14. 175 is how wide the tire is at the outer point, 70 is how tall (rim to outter edge) and 14 is the width of the rim it goes on. Is that right?
That's correct. In your example, the "70" - the height of the side wall - is a percentage of the width of "175". That is, the sidewall is 70% as tall as the tire is wide.
Ok, I think I've finally got it. I've never missed my TJ more though. It's easy with the american tires, Height, Width, and Rim.
I don't think anybody answered the question about the profile of the original tires (155R14 and 165R14). They were 82 series tires. And yes, 185/65x14 is slightly smaller diameter and 185/70x14 is slightly larger - either should work fine for you.
Terry. It's in the article. After talking to a number of older people in the tire industry that had worked through the cross ply to radial change it is unclear what aspect ratio the original radial tires offered as an option for the MGB could have been. It's possible the aspect ratio for the 155-14 tires was even higher than 82.
Certainly the later 165-14 tires supplied during the 70s were "low profile" 80 series ones.
All in all, there is not much difference between the recomendations listed. My prime concern is that people using the 175/70, 185/65, 195/60 tires are going to be unhappy with the MGs high speed cruising revs and noise.
"My prime concern is that people using the 175/70, 185/65, 195/60 tires are going to be unhappy with the MGs high speed cruising revs and noise."
That's where the O/D Transmission comes in.
Here are some 195/60 15's on a set of 15x6 Superlites I got from Hap (pre-burrito). It's way too much tire even for my new "Hot Rod" motor. But I think the really look good. By the way, that is the new "urban camo" paint scheme.
Have fun
Harry I love it.
It's a weird streak I have, but I really like stunning wheels on a "work in progress" car.
kelvin
