I’m currently working on version 2 of the Tyre Size Calculator, it’ll fix some inconsistencies in the current version and add a few new features that commentors have asked for e.g.
- Bike Tyres
- Mud Tyres
I’m also thinking of adding the option to specify the wheel width so you can see how fat or stretched the selected tyre size will be on a given wheel width.
If anybody has any comments of suggestions then feel free to post them below 
Include the % variation and the recommended maximum % variation advisable.
… Orv D
Hi
Could you please advise if I can replace my tyres which are 235/40/19 with 235/35/19 for a better and cheaper tyre choice?
Regards
Lee
Hi, I find your tyre calculator very useful BUT having repaired speedos for 50yrs I must point out that INCREASING the tyre size obove standard will REDUCE the speedo reading & not INCREASE it ie. a larger tyre makes LESS turns per mile so the drive cable / sender will turn LESS for the same distance travelled = lower reading… best regards John
hi,
for those with classics, can you add the 155 R 13 equivalent (think it is equiv to an 82 profile).
so we can tell diameter easily with modern profile tyres
cheers
bill
Is any adjustment of the tyre pressure required if a completely different wheel/tyre set is used, i.e., 225/60R16 on 6.5Jx16 wheels (winter set-up) in lieu of 245/45R18 on 8Jx18 wheels (original set-up)?
I’m getting great use out of the current version, thanks, but would like to see some of the ranges increased. For instance, I have a 145/95-10 tyre (not a mistake) and want to convert to 12″ rims, but the closest I can get with the drop-down lists is 145/80-10, so have to guess a bit to do the conversion. Thanks. Jeff
Visual tyre size calculator is a great tool for visualizing the results instantly. Slight tweaks are always recommended. I would like to suggest
1. a bigger tyre sized display in comparing sizes is a much needed feature. Will be useful in smaller display (screen) sizes to see the differences. Visualising in big LCD screens is fine now, but in small laptops and other smaller displays, it is difficult to make out the differences
2. Better font with anti aliasing is also be a welcome addition
3. It will be better if we can customize or have options to choose alloy wheel design with more spokes in the rim. Would be very useful for getting an idea about the final looks of the alloy – tyre combo.
It is a great tool. Wish you all the best to the brain behind such a tool. You can always make it better and even the best.
Regards
Mr. Nagendra
India
It would be good to see information about the rim requirements for the new/proposed tyres. Then I would know if I’m simply buying rubber or new hardware too.
Thanks Jon
I am currently using 225-45-17″ tires, is it ok if I use 225-55 tires on this ream
Although you would be able to fit these tires on the rims, you would have to worry about clearances. This is the same factory tire size I have on my car (225/45R17)and even going up to a 50R17 I’m getting a bit of scraping in winter in comparison to the factory tires. Of course, it all depends on the vehicle you are putting it on, and it’s wheel clearances, but with the increased diameter making the tires 22mm taller than factory, at full-lock steering it comes a lot closer to the interior of the wells. You’ll also have to factor in that compared to the factory tires, this is a 6.7% increase in size, meaning that doing 60MPH on your dial, you’ll actually be doing closer to 65MPH. Watch them speeding tickets.
I will look forward to the next version although I find this one very usful anyway…
What I would like to see within the new version, is a comparison chart in case anyone such as myself are deciding to increase or decrease my cars standard tyre size, so maybe an alternate equivalent option perhaps, still showing the effect on speed, Height etc, for instance…
235/45 18 Tyres are quite expensive at aprox £180 each, however you can get 225/40 18 at aprox £120 each and may consider losing 10mm width and save up to £80 a corner, well it all adds up…
I think the calculator works really well all ready, so it would be good if any major new features did not impede the the current ones. A lot of what is being requested can be derived from understanding the information that is all ready displayed.
I second Ken Turner’s request for the sizes such as 31 x 10.5 x 15, and Siegfried’s request for diagramatic explanations.
Thank you for the calculator in the first place, I couldn’t have chosen my next set of tyres without it!
would be nice to be able to print out the data for the old and new size comparisons.
image showing “front on” profile of tyre in relation to the rim width (stetched, bulging sidewall, etc.)
I would like to see the effects which happen to the same size tyre depending on rim width.
currently on my campervan i am running 215-55-16 tyres all round however front rims are 7j and rears are 8j so profile looks less on rear than front and looks rubbish, it would be great to calculate profile over stretch on rim. thanks Martin.
An update with tire width (metric and inches) would be helpful. I know the first number (eg 185) is the width, but is that the tread width?
Will 245/40RZ20 TIRE FIT ON MY 06 LEXUS GS300 IF I TAKE THE INSIDE COVERS OFF THE WHEEL WELL OR WHAT DU U RECOMMEND BECAUSE I LKE THE 20″ RIMS BUT IT’S SITTING LOWPRO ON 35 NOT ENOUGH I WANTED JUST A LIL MORE MEAT ON THEM SO I WON’T BEND THE RIM AS EASY.
If you can layer the tires over each other with straight on and sideways view that would be great. Also if you can show whether one tire can be substituted for a given tire or not and at what point it becomes unsafe that would be helpful. Thanks for everything
The profile options only go up to 85% some tyres have a higher profile (90%)
Tom
it would be helpful if effect on fuel efficiency of vehicle can be measured.
I praise you as i have found current version also very informative.
regards,
An option to select diff. rim sizes / Combinations / Designs
Just to reiterate ZJ Jeepsters comment – some guidance on offset would be handy. Congrats on the site.
1)Please stay with metric units – it’s great and so much easier.
2)Be uniform in the units when giving the charateristic dimensions of a wheel – i.e. use either cm or mm for the Total Diameter and the Rolling Radius and the tyre width etc. I prefer mm to cm here.
3)Please use the correct abreviation – km not KM (not that I noticed this mistake in the 1st version – just pre-empting).
4)For me there are 2 components – a rim and a tyre. When you assemble the two components you have a wheel! (Perhaps I’m the only one in North America who thinks this way.)
5)Perhaps I didn’t look carefully enough at the 1st version – but showing the meaning of the terms diagramatically would be nice. For instance, exactly what is meant by “Rolling Radius”?
6)Thank you for your great calculator.
Tyre pressures if it was possible
can u add the mileage differential in KM =))
So… any progress in version 2 ??
I would like to be able to change MPH to KPH.
Impact of the tyre size change. Interms of high speed impact details etc..
Specially adv and disadvantages.
– metric / imperial sizes both shown. (ie so we know as 235/85 16 is nearly 32″)
– switchale end view (to show comparative width).
– over/under speeds shown in imperial and metric.
Here’s a couple of things to add:
– High Flotation Tires
– Tire Width to Rim Width ratio with a “Acceptable”/”Warning” note
– What is the IDEAL tire to rim width?
– Rim offset calculator (to allow you to go from one width to another while minimizing the risk of damage to the wheel bearings)
Too narrow of a section width to rim width ratio becomes VERY dangerous due to the fact that the tire bead can come free of the rim easier. In addition, it can also cause the outer sections to press against the road and the center to lift up creating an unusual treadwear pattern. However, I know you can usually get away with wider tires than rims. But, how wide is too wide? I’ve seen people run very wide tires for their rims and not have problems. But, I also have seen some tires that just wear funny because of how they’re made. Too wide of a tire causes the tread pattern to baloon out causing uneven treadwear and certain handling issues.
Currently, I run P255/70R15 on my 15x7J factory rims. According to research I’ve done, the manufacturer provided multiple sizes for my Jeep. They were 215/75R15, 225/70R16, 225/75R15, 235/75R15, and 245/70R15. My door tag says 225/70R15 mounted on 15x7J rims.
Interesting. isn’t it?
Cheers
Hi Insomniac. I’ve been trying to find a tyre size calculator that includes rim-width in it’s inputs – this can have a considerable effect on sidewall height, i.e. a 205/45 tyre on a 8″ rim will be seriously stretched, but will be baloon-like on a 6″ rim.
If you can work out how to incorporate this (preferably along with a cross-sectional view) I can guarantee you’ll get loads of hits just from the euro-look brigade, let alone the ricers, pro-tourers etc
It would be nice to have revolutions per mile/km, speed difference (obviously only if speedo is correct) Maybe even RPM at given speed
Maybe…..
Reduction or increase in engine revolutions at a given speed.
For example, the reduction in Engine revolutions by fitting 275/75 from original 265/70 at a steady indicated 120 kph
Thanks
I’ll include those stats in the next version for you
For those of us wanting to size a suitable space saver wheel, it would be good to have the calculator work down to the 115 and possibly below width ranges.
a 3d effect to see all the angles of the tire
give me please code of calculator for my site
Hi Sergey,
Unfortunately I do not give out the code for my utility. The calculator generates most of the money to pay for my hosting at the moment so I don’t want to reduce that by handing the code out.
I’ll email you at the address you provided about a branded version tho.
taste isnt factory standart equipment….
Hi insomniac, do you mind If I have a link to this calculator? perhaps at some stage you would link back to me?
Any chance of getting a conversion rate for tyres that are labelled 31 x 10.5 x 15 or similar, so going from 235/75 R15 to 30 x 9.50 x15 could possibly be helpfull or indeed many many other sizes.
Hi Ken,
It shouldn’t be a problem to add in the option for these notations. Its mainly 4×4, mud tyres and light trucks isn’t it?
I would like to suggested you to enable us to fit or select the rim type as well. So, we may select the best rim that nice to be fit to our vehicles and know what best behind it with your powerful calculus..
You may link it with rim manufacturer or supplier. At the same time U might be their sole distributor or agent thru web or online! Seem cousin of e-bay…..cheese !
Hi Nicerule,
Thats a good idea, ambitious… but good. I’ve already had a few companies interested in using my calculator but so far I’ve declined, the amount of time I have to spend on these little projects is decreasing quickly as I’m soon to be a father so right now I’m hoping I can just get V2 finished before then!
PS, do you run paultan.org? Its an excellent site
Hi there, is there any chance of getting a copy of this calculator? It is the BEST thing I have seen on the web to help me with working out stuff but unfortunately I am pretty far off the road and dont have internet. Any chance of being able to get it ?
Hi netminder,
This is the first time I’ve checked my blog in at least a month. My daughter was born three weeks ago, 4 weeks early so I’ve been super busy elsewhere.
I’ve a couple of completely unrelated iPhone apps in the pipe that are only about 10% finished. Once I’ve finished them and I’m comfortable with the submission process I’ll definately think about doing the tyre calc as an app. Dunno if it’d be worth 59p/99c tho.
Maybe you should develop it as an iPhone app, and sell it on the Apple App Store. That way you can still make a few bucks, and keep us tyre nuts happy.
That would be grand! Really appreciate it if you are able to let the old one out when the new one comes in
It’s a really top notch little program!!
Hi Jimmy. I’ve been emailed a few times about this but I’m reluctant to release a flash executable as the calculator accounts for about 80% of my sites overall traffic and at the moment the resulting ad revenue is paying for my hosting. I’ll keep your request in mind and may release a cut-down version of the old calculator once the new one is ready
a nice bit to add would be… I know what my “Factory” wheel and tire sizes are, if I want to increase the radius of the wheel, what size tire would I need to keep the same rolling radius as my current stock set up.
Thats a great idea Tony. I’ll add that one to the list and get working on it. Thanks
I’d like to be able to change from mph to kph, and also change the speeds like at 10kph, 15kph, 40kph or 100kph. I also like your ides of seeing how sterched a tire will be. that would be good.
I’ll definately include a switch for mph/kph, maybe even a cm/mm/inch switch?
would be nice if the graphics include the type of vehicle and different rim shown fitted so that we can actually see our vehicle is shown with the type of rims selected.