MG MGB and MGB GT Tech Talk
Hi All, Need to replace my tires and it seems the sizes to use are 175/70R14 or 185/70R14. Some threads say that the 185's are to wide for wires. Would those of you using the two different sizes give me your take on how they work for you? I know that this topic has been beat to death, but a search really didn't answer my questions.
Thanks, Mike
71 MGB OD & Wires
63 TR4 Surrey Top
I run 195/65/14 with Dayton spoke and have no clearence issues.
I have 185s on my stock '73 wires and no problems. They fit just fine. Make sure you clean and sand, if needed, the inner portion of rims where tubes will be in contact with the rims and have a good band covering the spoke nuts on the inside.
Are the Dayton wires the same width as standard wire wheels?
5.5" wide with little more offset, which in my mind, tells me this size would work with stock spokes. They are not even close to rubbing no where.
But isn't there more than the rubbing issue? A 185 might give a bit more rubber on the road, but might lose something by having a squishier feel from more sidewall bulge than a 175. But more comfort, if that's what you're after.
I have stock wires, 4 1/2" , which I understand might be to narrow for 185's.
Thanks, Nike
71 MGB OD & Wires
63 TR4 Surrey Top
Well it depends on the second number Derek which is the sidewall height ratio when compared to the width, the first number. I always try to fill the wheel opening up, that look I think is a better look, but that's just me. I can tell you, you wouldn't want a better handling street B than mine, it carves a corner pretty darn good, even better I'm sure when I convert it to bolt on wheels. On tire sizing for example take a 175/7014's side wall hieght would be greater than 195/60/14, then the 195/65/14 side wall height would only be roughly .120" taller than the 175/70/14. If you campare the 175/7014 to 185/70/14 you gain about 7mm or rougly .280" in height.
I'm running 185/70 R 14 on 72 spoke chrome daytons and have plenty of clearance.
But we're back to rim width vs tire width. Put the same (whatever) size tire on a 6" rim and a 4.5" rim and the sidewalls are going to be more vertical on the 6" wide rim. On the 4.5" rim, they're going to curve inwards more and give a more comfortable but squishy ride.
Not claiming the following is the gospel truth:
"Too wide or too narrow - does it make a difference?
Given all the information above, you ought to know one last thing.
A rim that is too narrow in relation to the tyre width will allow the tyre to distort excessively sideways under fast cornering. On the other hand, unduly wide rims on an ordinary car tend to give rather a harsh ride because the sidewalls have not got enough curvature to make them flex over bumps and potholes. That's why there is a range of rim sizes for each tyre size in my Rimwidthulator above. Put a 185/65R14 tyre on a rim narrower than 5inches or wider than 6.5inches and suffer the consequences. "
Source: http://www.chris-longhurst.com/carbibles/tyre_bible.html
Here's an interesting read on the subject:
http://www.mgexperience.net/article/tire-sizes.html
One thing I would note is that the OE tire size listed at the Tire Rack is wrong! They list a 185/70R14 as standard, but if you look at the specs of most manufacturers, you'll see that 185 is recommended only for 5-6" (sometimes 5-6.5") rims. This would be fine for the wider Dayton's, but not officially recommended by the tire manufacturers for original Dunlop wires. Also, as pointed out above, the performance would probably begin to suffer anyway due to too much sidewall curvature.
According to the link above, the best replacement would be a 175/70R14.
Good luck!
-Kyle
Tire Rack's only partially wrong.
Quoting "Original MGB" (pg. 96):-
"Cars with cast alloy wheels in 1979-1980 had low profile tubeless tyres, of size 185/70x14, either Dunlop SP4 or Uniroyal Rallye."
These are the LE wheels. 5Jx14"
I agree with you 100% Derek, you should not exceed the recommended tire size rim width by more than say 1/2 with any given tire size. Normally most tire sizes have a 1/2- 2" spec range for rim width on any given size.
I had a set of 195/75 R14 Pirelli P400 tires on the original wires for a few years. Larger diameter tires roll more smoothly, and drop a few hundred rpm at highway speeds.
No clearance issues but they may provide a softer ride. They still had excellent handling compared to most sedans, the car still had great balance and cornered like it was on rails, with no squealing.
Last year I got a set of 15x6 Minator wheels and I am using 205/65 R15 Michelin MXV4 tires. The handling, cornering, and braking abilities of the car went from excellent to amazing!
The only downside is that I have had occasional tire rub, though it's no fault of the tires. There is plenty of room for this size tire in the wheel well, but the offset of the wheels is about 1cm too far to the outside. I had to roll (hammer actually) my rear fender lips. The tires don't rub in town at low speeds, even over speed bumps, but when I take it on the highway, at highway speeds through dips the rears do make contact with the rolled lips. I am going to try a pair of stiffer rear shocks, and if that doesn't stop the rub, then the next set of tires will be 195/65 R15.
Tires are 'sized' according to Tire and rim Association guidelines. Those guidelines state that the tire is sized at a rim width 70% of the tire section size, and allowable rim widths range from (IIRC, it's been almost 25 years since I last looked) 50% to 100% of tire section size.
for a 4.5" wide rim-
4.5" divided by 0.7 (70%) x 25.4 mm/in = 163 mm, so optimim tire width (in a production size) would be 165mm. Aspect ratio would be user's decision based on gearing, apperanace, and load carrying requirements. Narrowes tire allowed withing the scheme of the reccomendations would be 125mm, widest a 225.
OK, that information is OK for selecting a tire that would work with the rim width and not cause abnormal stress on the bead.
Narrow tires that are available won't have the load carrying capacity for the car unless you blow them up to like 100 psi (remember Hunster S thompson in Fear and loathing in Las Vegas?) so they "handle like a lotus"
A wide tire will wander back and forth under the rim, and roll the tread up when cornering, causing what I deem to be poor handling.
On a 4 1/2" rim, I personally wouldd go no wider than 185mm (wheel 62% of section width.)
There should be a whole lot more to sticking tires on wheels than just what fits in the wheelwell. And don't depend on most tire shop operators to have a clue. Some do, many don't
MudSnow Wrote:
185/70/14 is fine on stock wires.
I like this size better than 175/70/14.
The type of tire makes a big difference. If you buy a mushy, soft sidewalled, touring tire, you'll be letting the car down.
Get a good performance/high performance tire and you'll find an excellent "footprint", stout sidewalls, better handling and braking.
165/14 Vredestein Quatrac 2s on 4.5 original size wires. Excellent profile, nice soft ride and no squishy feeling.
Excellent tire and well priced? Sumitomo HTR200. 175/70x14 from Tirerack.com - $39 each
http://www.tirerack.com/tires/Compare1.jsp?width=175%2F&ratio=70&diameter=14&startIndex=0&search=true&pagelen=20&pagenum=1&pagemark=1&manufacturer=Sumitomo&RunFlat=All&x=52&y=9
I'm running Michelin Harmony 185-70/14 on standard 60 spoke 4.5" chrome wires and love them. No clearance problems, lots of contact patch, and great ride. Harmony's rated high across all conditions in Tirerack specs.
Sorry to get OT for the moment, great discussion about tires but I need to know.........Paul, what kind of headlights are those?
Ok back to the topic. I hope Mike isnt too confused. There are good explainations here and Mike needs tires! I think a little info on his driving habits would be helpful.
Mike?
rrmgb Wrote:
Thanks for all the replies. I went with 185's as that was all I could find in my area ( small rural town in SE Colorado ). Web site said that they would fit rims from 4.5" to 6". Robert, my driving varies from daily driver to crusing to hard on twisty back roads. I don't have any impressions yet, as shortly after mounting my fuel pump went out. Pull and repair today. I had Avon 165R14 Turbosteels on, with rotting sidewalls, so this has to be an improvement. I priced Avons on the web at 238.00 each! Must be because they're period correct. LOL. Again, thanks for all the input.
Mike
71 MGB OD & Wires
63 TR4 Surrey Top