Mileage Issue

[DanY]

I recently installed Bajaron’s shock adjusters on my 2016 RTL as well as new Vredestein Quatrac-5’s for the new front tires (175/55R15) Back tire is a new General Altima43. Previously I installed Bajaron’s sway bar kit.

I ride pretty aggressively and I know it’s a small sample (350 miles) so far but my mileage has dipped from a normal 35mph to 30mph.

The front tires are inflated to 18psi and back tire at 28psi.

Anyone else notice a mileage drop?

[CopperSpyder]

I think Loss of mileage with the setup you have is common, Good Tires, Bajarons equipment, will tend to change the way you ride. Instead of rolling out of the throttle when coming to a corner you probably now roll into the throttle when going into a corner. The setup you have gives a driver more confidence in the Spyder to stay in the throttle more even more so at highway speeds also. So now you go to fast and get less MPG.

8 to 10 psi to much in the rear tire. Hope you checked the bearings before you put the tires back on. Could be just bad summer Gas blend.

[BajaRon]

I think Loss of mileage with the setup you have is common, Good Tires, Bajarons equipment, will tend to change the way you ride. Instead of rolling out of the throttle when coming to a corner you probably now roll into the throttle when going into a corner. The setup you have gives a driver more confidence in the Spyder to stay in the throttle more even more so at highway speeds also. So now you go to fast and get less MPG.

As good an explanation as any I've heard. Other possibilities include, going from worn tires (smaller diameter) back to the original diameter (with brand new tread). As well as a new tire with more tread usually has more rolling resistance that a worn tire with less tread. Another aspect is that the OEM Kenda's (at highway speed) usually have a 2-1/2" to 3" contact patch with the roadway. That is why they wear out in the middle leaving plenty of unused tread on each side.

A good car tire tends to keep the entire tread area in contact with the pavement. This will also contribute to higher rolling resistance and lower fuel mileage.

But the biggest culprit would be if you went to a 215/60/15, or any rear tire with a larger than stock diameter. This will not reduce your actual fuel mileage. But it will register fewer miles for the same distance traveled comparted to the original 225/50/15 tire. A larger diameter tire will, of course, lower tire RPM at the same speed. So, you might not be suffering the mileage drop you think you are.

[BLUEKNIGHT911]

As good an explanation as any I've heard. Other possibilities include, going from worn tires (smaller diameter) back to the original diameter (with brand new tread). As well as a new tire with more tread usually has more rolling resistance that a worn tire with less tread. Another aspect is that the OEM Kenda's (at highway speed) usually have a 2-1/2" to 3" contact patch with the roadway. That is why they wear out in the middle leaving plenty of unused tread on each side.

A good car tire tends to keep the entire tread area in contact with the pavement. This will also contribute to higher rolling resistance and lower fuel mileage.

But the biggest culvert would be if you went to a 215/60/15, or any rear tire with a larger than stock diameter. This will not reduce your actual fuel mileage. But it will register fewer miles for the same distance traveled comparted to the original 225/50/15 tire. A larger diameter tire will, of course, lower tire RPM at the same speed. So, you might not be suffering the mileage drop you think you are.

I discovered and now recommend the Q-5's .... they are very sticky tires .... The RT43 in the rear ( where mileage is recorded ) is exactly what Ron said. Because of the change in circumference ( larger ) it is reporting less miles than the OEM tires...... and 28 psi is way to hight for that or any Auto tire used on any Spyder .... I recommend 17-18 for the rear ( only ) ..... welcome to the Vredestein tire club ..... .... Mike

[DanY]

Good info!!

Any recommendation for tire pressure on the front tires?

[Peter Aawen]

If you are ryding at the same indicated speed on your speedo as you were prior to the tire change, you are very likely now ryding somewhat faster than you were before! The difference may be only 2 or 3% faster, but just as likely it may possibly be as much as 8 or 9%, and is very likely to bring your ACTUAL speed over the ground much closer to being 'truly ACCURATE' than it was when you were still running the (worn) Kendas, AND your trip meter/odo is now very likely telling you that you are travelling fewer miles too! Once again, it'll be bringing its reading closer to a truly ACCURATE distance than it was before, when you were running the already 'notoriously small' Kendas that gave you some very optomistic speed and distance travelled readings even BEFORE they wore all their tread off and the readings became more inaccurate/far more optimistic!!

Check your speedo against an onboard GPS - even a 'street directory' type GPS or the one on your smartphone is likely to be accurate enough to give you a pretty good speed reading out on the open road, and I reckon you'll find that your 'dash reported' speed and distance travelled info is now within a mile or two of the GPS indicated info, instead of being the 'anything between 3 & 10% optimistic/over' that it would've been with the OE spec Kendas fitted!

And before too many people get all carried away with how their 'Kenda equipped' Spyder is more or less accurate than that, the inaccuracies in 'factory spec' speedo & odo/trip meters can be and usually ARE somewhat different between individual machines, even those that roll off the production line consecutively; and this level of 'inaccuracy' is effectively mandated under International Agreements between Governments & Manufacturers that effectively specify all speed & distance measuring devices fitted to motor vehicles may read OVER the ACTUAL true speed &/or distance covered by anything up to 10%, but they cannot read UNDER the true/accurate speed & distance!! And since the vehicle manufacturers who may be subject to penalties if their speedos & odo/trip meters lead their operators to believe their vehicles are travelling any slower than they really are/their true speed or travelling less miles than they really are on OE Spec tires & inflation etc, do you reckon too many of the manufacturers bust a gut to make their speedos/odos/trip meters are any closer to 'strictly accurate' than they need to be?!? Or might they just play it safe and aim for somewhere towards the middle of the 'permissable/acceptable range'?!?

BTW that % error CAN be different (& often IS different) between the speedo and the odo/trip meter on any given machine too!! So don't just assume that because your speedo was reading 10% fast that your odo/trip meter was also reading 10% more miles travelled than you really covered!! Sure, it COULD have exactly the same optimistic error, but it may not necessarily have the same error!!

PS: Recommended Tire pressures for 'non OE Spec Kendas'; ie, any a/mkt auto tires that you may fit (which are NOT Kendas) that have load ratings that exceed those on the Kendas are probably going to be somewhere in the range of 16-18 psi up front; and 14-18 psi or maybe even 20 psi on the rear, varying a little for your individual needs/wants & loadings, ambient temps etc. Larger tires generally need a little less air than a smaller tire in order to support the same given load, so running slightly larger tires up front suggests that you should probably be running slightly lower pressures.... and anything over 20 psi in a 'real' auto tire on the rear is probably a little high! But if you like to risk the harsh ride, lesser traction, excessive wear on tire & suspension, et al which that brings simply because it 'feels better' to you or for any other reason, then that's fine by me!

[BLUEKNIGHT911]

Good info!!

Any recommendation for tire pressure on the front tires?

Peter said it accurately ...... Like me, He knows tires also ..... Mike

[Revalden]

My tire sizes are listed below 17psi front, 18psi rear. I enjoy riding my Spyder soo much and I also ride aggressively and I don't care about the gas mileage. However, I've rarely refilled the tank with more than 6 gallons @ around 225 miles ~ 37mpg.

[DanY]

Never gotten 37mph.

But typically I can go 185miles before looking for a gas station. After 185+ miles, I’m ready for a comfort stop anyway.

I think I’ll try 17psi all around and see how that goes.

[Curlytops]

Tyre pressures always start a good debate.. like oil!..ride with whatever feels comfortable for your riding style... start lower and increase tyre pressure until your happy..for me the lower tyre pressures in the front made my spyder feel very wallowy in corners.. too much tyre wall roll for me. I ride with 21 in the fronts and 28 in the rear and it suits my riding style... and i dont hang about!

[Peteoz]

Tyre pressures always start a good debate.. like oil!..ride with whatever feels comfortable for your riding style... start lower and increase tyre pressure until your happy..for me the lower tyre pressures in the front made my spyder feel very wallowy in corners.. too much tyre wall roll for me. I ride with 21 in the fronts and 28 in the rear and it suits my riding style... and i dont hang about!

Just to put things in perspective, Curlytops, what type of Spyder are you riding, what tires do you have on, and what other mods (like say... Ron’s sway bar) do you have (if any)? It can all make a difference

Pete