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Tyre width


UKTJ

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I am looking at new tyres and considering what width to go for.  What width tyres do others run, why did you go with that width?  What do you feel are the advantages of a wider tyre over a narrower one?  What do you feel are the advantages of a narrower tyre over a wider one?

 

All and any input much appreciated.

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That’s a good debate… 

I’ve had this conversation a lot over the years of being a 4x4 Owner …

im come to the conclusion that it’s just down to personal choice…

I personally run wide tyres always have … normal 12.50 … wide .  have for the last 20 odd years on my two wranglers 

I personally like the look … I think it improves road handling for corners … & I like the way they preform off road ..

Even with out airing them down .

 

 

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I have to agree with John, there are pros and cons to both, I tend to prefer a narrower tyre, 285s ( if that counts as narrower) but really it is down to personal preference and what you think looks good on your Jeep.

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There is also wheel rim width to consider. A 12.50 tyre will be wider on a 10" wide wheel than on an 8" wheel, the amount of tread on the ground will be the same. My preference is for an 8"-9" wide wheel with a 12.50 tyre.

 

A 33x12.50R15 on a 15x8 wheel handles a lot better on tarmac roads than a 35x12.50R15 on the same wheel due to less sidewall flexing when steering. A 16x8 wheel would probably be better for street handling and off road use on a 35" and a 17x9 wheel on a 37". A wider wheel reduces sidewall flexing and improves steering response on tarmac but this can also reduce off road performance.

 

I generally drive slower on 35" tyres than I do on 33" tyres. I recently decided against moving up to 37" tyres not just because of the additional mechanical stress on my Jeep but on me too. As I am not getting any younger, I decided that a 35" tyre was heavy enough for manhandling.

 

Another important factor to consider is availability of the chosen size in a few years time. This is really difficult to predict but it makes sense to pick a size that is popular now and likely to remain popular until you are ready to buy new wheels. During my time as a Jeeper I have seen BFG and others get rid of 33x9.50R15, and 3x10.50R15 AT and MT. The 33x10.50R15 MT has returned as a KM3 and KO2 but only from BFG. Both of these were popular sizes for UK YJ and TJ owners in the late 90's. 'E' marked 37x12.50R15 went extinct ten years ago, but it was a size that I considered in 2006 as 17" versions were scarce and very expensive. The 35x12.50 is not as popular in Europe as the 33x12.50, so I am keeping an eye on UK availability regularly as the number of brands for this size is falling.

Edited by V
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Many years ago I attended a Steam & Vintage Show in the West of England. It was a washout!

Only vehicles allowed to move around the site were a few  service vehicles but only with fairly slim mud tyres. I had a XJ then (lovely motor!) and did get around ok. Combination of tyres and driver!

Toyota and Landy with dirty great wide muds got stuck. Whilst I was helping them an old guy in an Austin 7 came chugging up the field and straight past us. No bother! Skinny little tyres, not much weight, only 2 wheel drive, but careful driving. You can't really boot an Austin 7!

My thoughts for what they are worth - skinny tyres more pounds per square inch on ground = more grip. Wide tyres, load spread over bigger area, less grip. I run on muds, but not big fat wide ones. I believe they are better in snow and ice also.  My own thoughts and experience and it depends what else you do with your truck.

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My experience is perhaps different to many, being based upon some 'landie' use on farms etc plus motor sport - 10yrs dirt racing and 30 yrs tarmac racing both as a driver in the early days and always as  mechanic.  This ,for me is a basis for my tyre sizes used. Tyre width is  about the weight of the vehicle and the surface you are driving on.  Consider a stiletto heal versus a big wide boot as an extreme example.. Grip is about the friction one can generate between the surface and the tyre rubber added to other factors such as compound(How soft is  the rubber) .  Can you cut through the slick rather than ride on top of it?  Dirt /loose surface racing you see few really wide tyres and on tarmac, 'wets' are narrower , softer,with lots of sipes . Big wide tyres can work, I am told, on very deep snow etc but we don't see much of that here and you probably get stuck anyway.

The first thing I think you should consider is what percentage of your driving does what?  What qualities are important to you?  Traction? Tyre strength?  Road noise? Road comfort? On road handling? Cost? Looks? JOC type events? Green Laning?  Extreme off road ? Rock crawling?  Wear rate? What other mods are you prepared to under take for your tyres?

 

I don't know what you want but as an example this is me.

I want MTs but No 1 is low road noise and ride comfort ie less  'bumpiness'  2nd wet road predictability 3rd good traction off road and ground clearance for JOC type events and some lanes. I enjoy  driving in snow.  Value for money. I do not place looks above practical results. ( aside my GC has big wide tyres. gr8 generally but poor in snow, the car becomes a toboggan at 30-40 mph!)

So, up until now I  lean toward a narrower width and currently run 31x10,50x15" on the YJ. These provide excellent traction especially where there is a greasy/gravelly /mud surface to cut through. Considering she has no lockers traction performance  is not bad as many have seen.

I run  Maxxis Mts. I find them excellent for my requirements and will shortly upsize to 33s and will buy them again for the third time. I have posted else where re my experiences but I have used BFG, Grabber and Coopers. I may have to upsize to 12.50 due to availability but we shall see. it may be that 12.50 will need extra flares!

Hope that's of some help.

 

 

Ps my nearly new 31s will be up for sale soon plus a smaller set of BFGs. enquiries welcome.

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I used skinny 33x9.50R15 BFG MT for a while and they were terrific in British mud, but they were very scary on wet tarmac with the lift I had. When I changed to 33x12.50R15 there were some obstacles at familiar off road sites that I couldn't easily conquer without airing down. On the street the 12.50 width tyres made the Jeep feel safe again. It's been a compromise between traction and ride performance that I have been happy to make for twenty years.

 

A very rough guide for choosing tyre size for stability is for every inch of lift, be that in suspension and or tyre section, the track width should be 1/2" wider or more. This can be achieved by selecting the right wheel offset and tyre width.

Edited by V
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Yep, V's right its all about the set up you have and what you want. His comments sum up exactly why I personally don't want to have an even higher suspension lift . I'm happy to stick with my 2" plus  my body lift with larger diameter tyres. The disadvantage off road wise for me  is my hard top, which I tend to keep on. This is because it contributes( its heavy!) to raising my centre of gravity. Hence why I don't want a higher suspension lift.

Poor  grip on a wet public highway is grim but without  control and predictability  whatever happens is worse in my view. One big name make I had 6/7 yrs ago were awful. I had a terrible experience on the 'Peripherique' in Paris. They had already shown they had  little grip despite trying different pressures etc. before. It was a sudden very heavy storm on a dry road that caused the surface to be like an ice rink for me. The issue was, the tyres were unpredictable and slithered in any direction. Just about anything stimulated it. I came out of a slip road sideways!  Very scary and it was virtually impossible to slow down which I was forced to do in very heavy multi lane traffic!

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My stock tyre is a 225/75/16 which I believe equates to about 29" x 9" in round numbers.  I am looking at a 2" maybe 2.5" lift, depending on where it settles, using the above rule of thumb that suggests an 11" to 11.5" tyre.  Based on that a 255/85/16 (10") is likely to be a bit too skinny, so probably better with something like a 285/75/16 (11.2") as a minimum.  Anything more than 10.5" is going to require either spacers or new wheels with less backspace than the stock ones, so the credit card is going to take a bashing 😂

 

If I went for spacers are there any particularly good ones or bad ones to avoid?

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Calculating total lift:

    29" diameter tyre to 33" = (33-29)/2 =  2" in the tyre

+ 2.5" suspension =

4.5"

 

Recommended track width increase: 1/2" wider for every inch up

4.5" / 2 = 2.25"

That is 1-1/8" per side.

 

  • A set of 1-1/4" spacers with OEM wheels and any tyre width 9" or more gets you in the stability range.
  • 285/75R16 on OEM wheels will also be in the stability range but I don't know what the tyre clearance will be like on the front axle for steering.

I used 265/75R16 (32") on a 2.5" SkyJacker TJ lift kit with OEM wheels and flares. I am fairly certain I used 1/4"(6mm) spacer discs on the front to reduce the backspace from 5.25" to 5" for steering.

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15 minutes ago, V said:

Calculating total lift:

    29" diameter tyre to 33" = (33-29)/2 =  2" in the tyre

+ 2.5" suspension =

4.5"

 

Recommended track width increase: 1/2" wider for every inch up

4.5" / 2 = 2.25"

That is 1-1/8" per side.

 

  • A set of 1-1/4" spacers with OEM wheels and any tyre width 9" or more gets you in the stability range.
  • 285/75R16 on OEM wheels will also be in the stability range but I don't know what the tyre clearance will be like on the front axle for steering.

I used 265/75R16 (32") on a 2.5" SkyJacker TJ lift kit with OEM wheels and flares. I am fairly certain I used 1/4"(6mm) spacer discs on the front to reduce the backspace from 5.25" to 5" for steering.

Ah, OK I did not understand fully before.  I also have a 1" body lift to throw into the calculation.

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The track width rule is not an exact science, it's just an approximate guide to make you think about stability when lifting a Jeep.

 

Modifications are likely to raise the height of the Jeep's Centre of Gravity which will have an adverse affect on handling. Going wider can help improve the handling sensation of the Jeep to the driver and passengers. It doesn't factor for a full load of passengers, a bigger tyre on a swing out tyre carrier, or a loaded roof rack or roof tent.

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Something else to consider

After I got my JK a 2.5" lift and Duratrac 315/70/17's fitted a few years back, went to cross a single track bridge, which I've crossed many times in the past and the sides of the tyres on both sides, rubbed all the way across, thought I was going to get stuck 😬

I now avoid that route to cross the river.

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That's an interesting point  Blue Star. I often go though places like that!

 

UKTJ, you asked about what wheel spacers?

I have used spacers a lot over the years both in motor sport and on the road.  Whilst I consider myself a beginner off road these are my thoughts that might help.

Firstly , buy a good make. I go for TUV approved. I have not bought any with this Eu approval  that have been poorly/ inaccurately machined. 

Many folk talk about being 'hub centric' . It sounds good . I believe they are suggesting that the central hole in the spacer is a tight fit on the centre flange of your hubs. This is rare in my experience. The thing is, any tight/interference fit means accuracy.  Whilst the spacers may be accurate your hubs will not be unless they are brand new and even then they may not be spot on. On my Yj all the hub centre flanges are slightly different (same hubs as yours I believe) because of rust/wear /cleaning/casting etc and different manufacturers too I guess. So ,hub centric on the hubs is a bit of a non starter for most. However the wheels must be hub centric on the spacers! At the end of the day the spacers themselves  are kept in place by the existing studs!

  I believe the problems some folk have is caused by bad fitting practices.  Make sure everything is perfectly clean and degreased. Use thread lock on the nuts/studs holding the spacers and torque correctly. I always felt that my Yj studs were too short so I have replaced them with stronger/longer. I used ''Dorman 610-449''. Easy /inexpensive job. Ask if you want tips on how. Finally, you must lubricate the wheel centre so that it pulls down properly onto the spacer hub when you torque the wheel studs.

Hope this helps.

 

 

 

 

 

 

 

 

 

 

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I think all of the old design cars I have owned from my youth up to my XJ have been lug centric. I used to think that hub centric wheels were only on vehicles that used wheel bolts, but they are on studded hubs too. The snug fitting shoulder of the boss on the hub is supposed to engage with a corresponding diameter inside the wheel. In theory, the weight of the vehicle is carried on this shoulder instead of on the studs. This is a worthwhile benefit to an off road vehicle with bigger tyres.

 

It is possible to buy plastic adapter rings that can be used to fill in the gap for mismatched hubs and wheels. These will ensure that the wheel runs true so that your balanced tyre rotates without vibration when you remove and refit the wheels. They may also reduce wheel to hub corrosion problems.

 

Sadly, true hub centricity depends on accurate machining of both wheels and hubs. The JK is hub centric and OEM alloy wheels run true, AEV Pintlers also run true. Perhaps all Jeeps on 5 on 5" PCD are hub centric? Some lower priced after market wheels have been found with out-of-round bores and likewise some hubs (drums and discs) that can also cause very difficult to isolate fit and vibration problems. The out-of-round or eccentricity inaccuracy is typically small 10-40 thou, or 0.25mm-1mm which is not easily detected by the naked eye.

 

I haven't thought about this before, but this may be a quality aspect to check for reconditioned wheels that may have suffered heavy bore corrosion in their previous life.

Edited by V
The balanced tyre paragraph wasn't clearly explained
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Plastic shims are an interesting idea. I've tried making alloy ones on the lathe. Some hope! Maybe me or my kit not good enough! I like the point about used/refurbed  wheels too.

I've also considered some kind of filler but its a waste of time. Thread lock might  work, it sets v.hard but is useless in a vertical plane.

The problem of wheels corroding onto the hubs and sticking are another issue too, especially if you don't take them off frequently! I've recently experimented with a thin layer of silicone sealant wiped around the hub.  It isn't washed away and forms a sort of seal I guess to keep out water etc. This seems to work better. After about 6 months I had no problem with removal!  I think V and I talked about these ideas in another post. I have tried various greases, and found waterproof silicone grease with 20% Moly mix seems to work well for me. Good old copper grease doesn't last long a sit once did I found(modern rubbish!)

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