This might be a daft question, but I wish to change my front wheels from 15" to 14"…are there any issues doing this? They are non-alloy. The reason is I'm pulling a trailer and the car does struggle to maintain revs on even gentle slopes.

Thanks in advance.

Dan

depends how big your front disks are really.

your speedo will underread by a certain amount – you can calculate by how much by putting the 2 tyre sizes in a calculator like [url=http://www.miata.net/garage/tirecalc.html]this[/url]

I took a car from 16 inch to 13 inch & had no issues, it does depend on tyre size as well… I wanted a less stiff ride but a softer compound tyre so ended up with the same grip but in a more forgiving guise as well less unsprung weight.

Depending on circumference change obviously ride height & speedo reedings

Wouldn't it be easier to just fit lower profile tyres?

What's the car Dan? You will almost doubtlessly be able to but it's always good to check brake disc clearance, as mentioned above. I'm not sure it would solve your issue though.

If your car doesn't have the guts to pull the trailer, should it be pulling the trailer? Would 1" make enough difference for the (underpowered?) engine to now cope?

Your insurance might be a problem if you crashed.

Wouldn't it be easier to just fit lower profile tyres?

That's the solution.

Could you not just use the next gear down to make use of the lower ratios? Revving higher might affect MPG, but so will towing a trailer… And higher revs in the same gear is all you'd gain from smaller tyres/wheels.

Sorry, but totally idiotic idea. If you can't pull the load then clearly the car is not up to the job. Changing wheel/tyre diameter will have very little effect.

If you are underpowered for the weight you are towing you are probably also underbraked.
You are probably illegal in towing weight above manufacturer specifications
You would have an illegally inaccurate speedo
Your insurance would be invalid because of a significant modification to the car

If the tow weight is within manufacturer guidelines, you have an engine or clutch problem so spend the money on getting those fixed

Aye, bad idea for this reasoning. Your car is probably under-braked as well as underpowered. What car is it and what are you towing (weight, braked?)?

what the c`ptn says

there are new laws apperently re towing trailers, better check your licence details. I am old enough not to worry apparently 🙂

Cheers for the positive input…boo to the STW Joe Bloggs'es who assume I sailed up the clyde in a …etc.

Nissan Almera Petrol, 1.5l, towing an unbraked trailer, max total weight about 600kg. No license issues, car is legal to tow it but just doesn't do the job right. Changing down a gear on these hills actually isn't making a difference and I'm still not able to pull the way I should.

Will consider lopro tyres next time I replace them, or have a serious look at going down a size, understanding that it will give me higher revs and show my speed very slightly above what it actually is. It would do more than simply increase revs…it has the effect of increasing torque a little, just wondered if anyone knew the ins and outs of actually doing it.

Van next year when some cash appears!

Tar muchly
D

a pair of 285 degree grind fast road cams, combined with a decent tube exhaust manifold and decent induction will give more torque at a lower rev range, but might be financially a bit ( a lot actually) over the top. you're probably better off just getting something with a with more torque and a lower geared box.

Putting on smaller wheels or lower profile tyres will only have the effect of changing down a gear, so if that's not working then you're throwing money away. If the towing capacity is OK, sounds like your engine is not producing the power it should. Get a decent service which will be cheaper than wheels/tyres.

The Almera should be more than powerful enough (I used to tow a 500kg trailer occasionally with a 1.1 44hp, 4 speed!). What you have to accept is that when towing you can't pull like you would without the trailer unless you're way overpowered for day to day use, you're effectively adding 50% onto the car weight. As said, smaller wheel diam will just make normal driving less economical and require a change of tyres, driving in the correct gear and accepting that you can't accelerate like mad obviously is better. If changing down a gear doesnt help neither will smaller wheels, the % difference wheelwise is much less than dropping a gear. Try dropping 2 gears. But make sure your fans are functional!

Glasgowdan earlier that week…