Tire mismatch

[pitman]

Owner of a '65 Tiger. Has Dayton bolt-on wire wheels 15x6" (4" backspace).


Currently has 195/55/R15 (OD=595mm) Bridgestone Potenza RE002s all around. However, on the front the tires sticks out by about an inch, which isn't legal in Australia.


Question is, how different can the size of the fronts be compared to the backs? I see many people here with pairs having an OD difference of about 10mm.


The tires I'm looking at for the front are 175/65/R15 (OD=609mm) Dunlop BlueResponse, which I think will fit without me having to cut the body. Alternatively, if they don't fit, I could go with 175/55/R15 (OD=574mm) Bridgestone RE050A (asymmetric non-directional).



Also, I'm reasoning that asymmetric non-directionals can be sufficiently rotated within the same axle -- am I correct?

 

[michael-king]

Is it just your tyres or the actual wheel that is beyond the lip? I wpuld assume with a bolt on wire the offset on the hub would push the actual.wheel quite a way out ( are they a bolt on hub and wheel, or a wire with bolts onto the stock 4 bolt hub?

175s are likely to sit insde the lip.. 185 depending on your offset ... But if you are a full inch outside... That would imply its the actual wheel.. Maybe a little negative camber and some narrower tyres...

Are you in Adelaide ? You have a photo?

 

[pitman]

Stock hub, with wheel bolted onto it -- I figured the manufacturer-spec'd backspace would still dictate how much a 6" wheel sticks out (having said that, the total width of the wheel is 7", but again, I'd think the extra inch there is pretty standard difference between internal 6" measurement and the outer edge of the wheel!)

But yes, the wheel itself does stick out too far (about half an inch), and I figured getting a narrower tire like a 175 would at least reduce some of the extra bulge of the tire beyond the wheel (outer edge of tire is more like 1-1/2" beyond lip after measuring just now). TBH though I have no idea why given the specs (width and backspace) the wheel can be so prominent when I haven't heard others having the same problem.

How much negative camber can (?should -- the -1/2 in the specs?) I have for performance (I'm fairly aggressive around corners, though this is strictly a street car) if I don't mess with canter/toe from stock?

 

[Doug C]

Different tire sizes

I have to buy a set of tires for my Tiger and like the gentleman above mentioned my front tires stick further than the rear. Has anyone here experienced different sizes; narrower in front and wider in rear? Also what brand of tire are you using? My Tiger has a 302 and 5 speed. I am not planning on auto crossing it, just drive it and have fun with it. Just in case you are wondering I am running 14x6 Shelby wheels

Comments appreciated, Doug

 

[TAH_Tiger]

wheel backspace and tire size

To experiment with tire, wheel and backspace check here....
http://www.rimsntires.com/specspro.jsp

 

[michael-king]

They appear to be 72 spoke wires.. So should be somewhat bstronger than the usual sunbeam spec... You can run 1°neg camber without much trouble.. It will make low speed steering quite a bit heavier.. And id be more comfortable with neg camber on alloy wheels rather than wires... But it will tuck the tops in more.. You may want to look into the caster settings to help with self centering.. But beware the arae at the join on the fromt arch lip and valence from the outside wheel when turning... The tyre can catch the body there

 

[pitman]

Stainless 70-spoke. Dayton make strong wheels, so I'm not too concerned about the forces. Heavier steering tells me I'm onto the right idea then with the narrower (175mm) and slightly more rounded Dunlops to help counter that. Will try them with -1 camber and ~+4 caster. By my calculation, the combo of reduced tire width (by 20mm) and camber (600*sin(1) for a ~600mm tire height) will bring the top edge of the tire in by half that, or ~15mm, which looks like the best I can hope for.

From other threads, it appears that there's an almost consensus on having just a smidgeon of toe in(?)

 

[65beam]

mismatch

VTO wheels has a chart on their site that shows wheel size such as 13,14 , etc. They also show various wheel width and off sets. I have 13" X 5.5 inch on a couple of my cars. They recommended the 5.5 on this car.

 

[pitman]

Not sure about what's recommended, but they do list the following potential wheels:

Wheel Size Bolt Pattern Offset Lug Nut

13"x5.5" 4x108mm 19mm+ 7/16"-20
13"x6" 4x108mm 13mm+ 7/16"-20
14"x5.5" 4x108mm 22mm+ 7/16"-20
14"x6" 4x108mm 24mm+ 7/16"-20
15"x6" 4x108mm 24mm+ 7/16"-20
15"x7" 4x108mm 12mm+ 7/16"-20

https://www.vtowheels.com/1964-1967_c_1735.html


Meanwhile, Dayton recommends 15x6 w/ 4" backspace, at least for their wheels, which is what I got.

 

[65beam]

mismatch

I'm old school so I used my phone and called them. I told them what I had on a couple of my other Beams and told them about the changes Doug @ Tiger Auto made to the Harrington. It does have rear springs that match his Tiger and a modified front suspension that he built. The photo shows the results of the conversations. It has the 5.5 X 13 inch wheels This car is also shown in their gallery of cars.

 

[michael-king]

Not sure about recommended, but they do list the following potential wheels:

Wheel Size Bolt Pattern Offset Lug Nut

13"x5.5" 4x108mm 19mm+ 7/16"-20
13"x6" 4x108mm 13mm+ 7/16"-20
14"x5.5" 4x108mm 22mm+ 7/16"-20
14"x6" 4x108mm 24mm+ 7/16"-20
15"x6" 4x108mm 24mm+ 7/16"-20
15"x7" 4x108mm 12mm+ 7/16"-20

https://www.vtowheels.com/1964-1967_c_1735.html

Yes they recommend the appropriate offsets for the various popular whrel sizes used on the cars.

The 7" wheels are uaually used on the rears to sqaure the track.

Re the heavier steering thats will be more the result of increased camber. As for 175.. Id personally go 185 on a 6" rim and also to help woth tyre selection.. Not many sporting tyres in 175 especially on a 15" rim.

 

[65beam]

mismatch

Seven inch rear wheels would be a real problem on my car. Doug made a few changes to the car including rear shocks. No reason to start cutting the body just for the sake of saying wider wheels and tires are needed. That's why we followed the advise of the wheel experts and not speculators.

 

[michael-king]

Bob...

Lots of sunbeam owners run 7" wide wheels on the rear without modifying the bodywork, rolling the lips etc.... We can only aasume "your car" you are reffering to is the white HLM which is completely irrelevant to the posters question about his Tiger.

As for having issues with the shocks..assuming you have some odd modification to fit telescopics to your hlm... if that interferes with your wheels that seems to be yet another unique problem to whatever mods you have done to your car.... Lots of guys have done telescopic conversions on early alpines without your issues

Anyway your problems are completely irrelevant to the posters questions about his Tiger..

Seems like you are more interested in talking about your Harrington than helping contribute...

 

[65beam]

mismatch

Michael.
Thanks for your opinion. I keep forgetting that your knowledge of everything makes you a walking encyclopedia of everything Rootes. Maybe you should spend time writing a book detailing everything. In the mean time I'll continue to use common sense to ask the pros instead of listening to speculation.

 

[michael-king]

Thanks for your words Bob, I'll make sure to send you a signed copy.

Maybe you can check in with Doug while he does all the work and ask him to explain the difference between the Tiger rear axle and shock setup and that on a lever arm series II alpine and then whatever may have been done to your car to put telescopics on that would apparently cause issues with wirder wheels....

Infact if you are having such issues maybe browse the SAOCA site, a bunch of guys there have done telescopic conversions without having any of the issues you apparently exeprience.. One guy even sells a kit that should solve your problem.
Maybe ask their help.

Anyway...enough of the usual off topic sideline...

 

[pitman]

Re the heavier steering thats will be more the result of increased camber. As for 175.. Id personally go 185 on a 6" rim and also to help woth tyre selection.. Not many sporting tyres in 175 especially on a 15" rim.

This returns me to my original question: is there a *technical issue* with running 175s in front with 195s in the rear? I'm not concerned about fewer options -- I know I want Dunlop BluResponse, highly rated and grippy, and they come in a 175/65 R15. And after doing some homework have found that 175 is the minimum (though not the 'ideal' of either 185 or 195) recommended width for a 6" wheel generally. But I've only seen others here varying wheel width by 10mm (e.g., 205s in rear, 195s in front).

Now my reasoning FOR the 175s is that they'd be slightly narrower than 185s (though by not quite 10mm, just as 185s aren't quite 10mm narrower than 195s, since the wheel 'measurement width' used for reporting the wheel specs are 5", 5.5", and 6", respectively).

I figured that doing this would give me two benefits over 185s:
1) outer edge a tad closer to flush with the lip (above and beyond the ~5mm improvement I'd expect to get by reducing camber from 0 to -1).
2) narrower, slightly more-rounded tread would make turning a tad less heavy due to smaller footprint, no?

In terms of OD: the 175s are 608.5mm, while the Bridgestones currently in front (and to remain on the rear) are 595.5mm, and so I'll have to check that there won't be any chance of rubbing. If so, alternatively the Dunlops also come in 185/55 (OD=585) and 185/60 (OD=603).

 

[65beam]

Thanks for your words Bob, I'll make sure to send you a signed copy.

Maybe you can check in with Doug while he does all the work and ask him to explain the difference between the Tiger rear axle and shock setup and that on a lever arm series II alpine and then whatever may have been done to your car to put telescopics on that would apparently cause issues with wirder wheels....

Infact if you are having such issues maybe browse the SAOCA site, a bunch of guys there have done telescopic conversions without having any of the issues you apparently exeprience.. One guy even sells a kit that should solve your problem.
Maybe ask their help.

Anyway...enough of the usual off topic sideline...

Michael,
I bought a couple of the shock conversions, One was installed on the Harrington and taken off for various reasons and sold at a loss on e bay. It needs to be redesigned if you plan to drive over speed bumps or don't want to plow a dirt or gravel road. The bottom shock mount sets below the edge of the rim if using a low profile tire on 13 " rims. Do it right the first time and you don't have to do it over. Have you ever seen any of my cars other than photos?

 

[theo_s]

This returns me to my original question: is there a *technical issue* with running 175s in front with 195s in the rear?

Back when I got my Tiger it was equipped with LAT-70's with 205/60-13's on the rear and 175/70-13's on the front. The overall rolling radius was pretty much even.

You can absolutely do this with your tire sizes but it will make the car a bit more understeery than it would be with a more even tire size. Having said that, today's tires are so much better than the rubber back in the 60's, that you will still have a great driving experience.

One thing is that the outer face of the front wheels will still stick out compared to the rear wheels, and if the Australian regs mandate that the *wheel* must be inside the fender line and not just the tread surface of the tire, then you should also pursue Michael King's idea about adding some negative camber (which is a good idea in any case).

To Michael and Bob: With all due respect and thanks for the relevant information you've posted in this thread, it would be great if you could carry on your back-and-forth elsewhere...

 

[michael-king]

Back when I got my Tiger it was equipped with LAT-70's with 205/60-13's on the rear and 175/70-13's on the front. The overall rolling radius was pretty much even.

You can absolutely do this with your tire sizes but it will make the car a bit more understeery than it would be with a more even tire size. Having said that, today's tires are so much better than the rubber back in the 60's, that you will still have a great driving experience.
.

Agreed the smaller contact patch on the front will increase the Tiger's tendancy to understeer, but given it will be a known impact can be taken into account with driving style.

As for the modern tyres improving the driving abilities...they sure do... But the increased rear grip will also have a comparable impact of the front push... All back to that lovely reverse ackerman issue....

 

[Warren]

Maybe

The solution is a Dale's front end. As I understand it his standard rig has the potential to have the same type of sticking out on the front wheels clearly with one side more than the other. However I do understand that he is made a few custom with a slightly different track. I have a Hokansen sitting in the garage is it actually is narrowed for that same exact reason.
If you want to get truly spoiled drive one of these Mutt II style front end cars. I told a prospective buyer why spend all that good $ rebuilding a stock front end through a little bit more cash at it and make it a better driving car.
Not to mention being able to drive through puddles faster without throwing water and road grit all over your paint. Or be like a Lord Rootes pal of mine and elongate the mount holes and deal with it that way.